summaryrefslogtreecommitdiff
path: root/mm/ksm.c
AgeCommit message (Collapse)Author
2020-08-07Merge tag 'powerpc-5.9-1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux Pull powerpc updates from Michael Ellerman: - Add support for (optionally) using queued spinlocks & rwlocks. - Support for a new faster system call ABI using the scv instruction on Power9 or later. - Drop support for the PROT_SAO mmap/mprotect flag as it will be unsupported on Power10 and future processors, leaving us with no way to implement the functionality it requests. This risks breaking userspace, though we believe it is unused in practice. - A bug fix for, and then the removal of, our custom stack expansion checking. We now allow stack expansion up to the rlimit, like other architectures. - Remove the remnants of our (previously disabled) topology update code, which tried to react to NUMA layout changes on virtualised systems, but was prone to crashes and other problems. - Add PMU support for Power10 CPUs. - A change to our signal trampoline so that we don't unbalance the link stack (branch return predictor) in the signal delivery path. - Lots of other cleanups, refactorings, smaller features and so on as usual. Thanks to: Abhishek Goel, Alastair D'Silva, Alexander A. Klimov, Alexey Kardashevskiy, Alistair Popple, Andrew Donnellan, Aneesh Kumar K.V, Anju T Sudhakar, Anton Blanchard, Arnd Bergmann, Athira Rajeev, Balamuruhan S, Bharata B Rao, Bill Wendling, Bin Meng, Cédric Le Goater, Chris Packham, Christophe Leroy, Christoph Hellwig, Daniel Axtens, Dan Williams, David Lamparter, Desnes A. Nunes do Rosario, Erhard F., Finn Thain, Frederic Barrat, Ganesh Goudar, Gautham R. Shenoy, Geoff Levand, Greg Kurz, Gustavo A. R. Silva, Hari Bathini, Harish, Imre Kaloz, Joel Stanley, Joe Perches, John Crispin, Jordan Niethe, Kajol Jain, Kamalesh Babulal, Kees Cook, Laurent Dufour, Leonardo Bras, Li RongQing, Madhavan Srinivasan, Mahesh Salgaonkar, Mark Cave-Ayland, Michal Suchanek, Milton Miller, Mimi Zohar, Murilo Opsfelder Araujo, Nathan Chancellor, Nathan Lynch, Naveen N. Rao, Nayna Jain, Nicholas Piggin, Oliver O'Halloran, Palmer Dabbelt, Pedro Miraglia Franco de Carvalho, Philippe Bergheaud, Pingfan Liu, Pratik Rajesh Sampat, Qian Cai, Qinglang Miao, Randy Dunlap, Ravi Bangoria, Sachin Sant, Sam Bobroff, Sandipan Das, Santosh Sivaraj, Satheesh Rajendran, Shirisha Ganta, Sourabh Jain, Srikar Dronamraju, Stan Johnson, Stephen Rothwell, Thadeu Lima de Souza Cascardo, Thiago Jung Bauermann, Tom Lane, Vaibhav Jain, Vladis Dronov, Wei Yongjun, Wen Xiong, YueHaibing. * tag 'powerpc-5.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (337 commits) selftests/powerpc: Fix pkey syscall redefinitions powerpc: Fix circular dependency between percpu.h and mmu.h powerpc/powernv/sriov: Fix use of uninitialised variable selftests/powerpc: Skip vmx/vsx/tar/etc tests on older CPUs powerpc/40x: Fix assembler warning about r0 powerpc/papr_scm: Add support for fetching nvdimm 'fuel-gauge' metric powerpc/papr_scm: Fetch nvdimm performance stats from PHYP cpuidle: pseries: Fixup exit latency for CEDE(0) cpuidle: pseries: Add function to parse extended CEDE records cpuidle: pseries: Set the latency-hint before entering CEDE selftests/powerpc: Fix online CPU selection powerpc/perf: Consolidate perf_callchain_user_[64|32]() powerpc/pseries/hotplug-cpu: Remove double free in error path powerpc/pseries/mobility: Add pr_debug() for device tree changes powerpc/pseries/mobility: Set pr_fmt() powerpc/cacheinfo: Warn if cache object chain becomes unordered powerpc/cacheinfo: Improve diagnostics about malformed cache lists powerpc/cacheinfo: Use name@unit instead of full DT path in debug messages powerpc/cacheinfo: Set pr_fmt() powerpc: fix function annotations to avoid section mismatch warnings with gcc-10 ...
2020-07-22powerpc/64s: Remove PROT_SAO supportNicholas Piggin
ISA v3.1 does not support the SAO storage control attribute required to implement PROT_SAO. PROT_SAO was used by specialised system software (Lx86) that has been discontinued for about 7 years, and is not thought to be used elsewhere, so removal should not cause problems. We rather remove it than keep support for older processors, because live migrating guest partitions to newer processors may not be possible if SAO is in use (or worse allowed with silent races). - PROT_SAO stays in the uapi header so code using it would still build. - arch_validate_prot() is removed, the generic version rejects PROT_SAO so applications would get a failure at mmap() time. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Drop KVM change for the time being] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200703011958.1166620-3-npiggin@gmail.com
2020-07-16treewide: Remove uninitialized_var() usageKees Cook
Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var\(([^\)]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs Signed-off-by: Kees Cook <keescook@chromium.org>
2020-06-09mmap locking API: convert mmap_sem commentsMichel Lespinasse
Convert comments that reference mmap_sem to reference mmap_lock instead. [akpm@linux-foundation.org: fix up linux-next leftovers] [akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil] [akpm@linux-foundation.org: more linux-next fixups, per Michel] Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-09mmap locking API: convert mmap_sem API commentsMichel Lespinasse
Convert comments that reference old mmap_sem APIs to reference corresponding new mmap locking APIs instead. Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Davidlohr Bueso <dbueso@suse.de> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-12-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-09mmap locking API: use coccinelle to convert mmap_sem rwsem call sitesMichel Lespinasse
This change converts the existing mmap_sem rwsem calls to use the new mmap locking API instead. The change is generated using coccinelle with the following rule: // spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir . @@ expression mm; @@ ( -init_rwsem +mmap_init_lock | -down_write +mmap_write_lock | -down_write_killable +mmap_write_lock_killable | -down_write_trylock +mmap_write_trylock | -up_write +mmap_write_unlock | -downgrade_write +mmap_write_downgrade | -down_read +mmap_read_lock | -down_read_killable +mmap_read_lock_killable | -down_read_trylock +mmap_read_trylock | -up_read +mmap_read_unlock ) -(&mm->mmap_sem) +(mm) Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04mm: ksm: fix a typo in comment "alreaady"->"already"Ethon Paul
There is a typo in comment, fix it. Signed-off-by: Ethon Paul <ethp@qq.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Link: http://lkml.kernel.org/r/20200410162427.13927-1-ethp@qq.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-21mm/ksm: fix NULL pointer dereference when KSM zero page is enabledMuchun Song
find_mergeable_vma() can return NULL. In this case, it leads to a crash when we access vm_mm(its offset is 0x40) later in write_protect_page. And this case did happen on our server. The following call trace is captured in kernel 4.19 with the following patch applied and KSM zero page enabled on our server. commit e86c59b1b12d ("mm/ksm: improve deduplication of zero pages with colouring") So add a vma check to fix it. BUG: unable to handle kernel NULL pointer dereference at 0000000000000040 Oops: 0000 [#1] SMP NOPTI CPU: 9 PID: 510 Comm: ksmd Kdump: loaded Tainted: G OE 4.19.36.bsk.9-amd64 #4.19.36.bsk.9 RIP: try_to_merge_one_page+0xc7/0x760 Code: 24 58 65 48 33 34 25 28 00 00 00 89 e8 0f 85 a3 06 00 00 48 83 c4 60 5b 5d 41 5c 41 5d 41 5e 41 5f c3 48 8b 46 08 a8 01 75 b8 <49> 8b 44 24 40 4c 8d 7c 24 20 b9 07 00 00 00 4c 89 e6 4c 89 ff 48 RSP: 0018:ffffadbdd9fffdb0 EFLAGS: 00010246 RAX: ffffda83ffd4be08 RBX: ffffda83ffd4be40 RCX: 0000002c6e800000 RDX: 0000000000000000 RSI: ffffda83ffd4be40 RDI: 0000000000000000 RBP: ffffa11939f02ec0 R08: 0000000094e1a447 R09: 00000000abe76577 R10: 0000000000000962 R11: 0000000000004e6a R12: 0000000000000000 R13: ffffda83b1e06380 R14: ffffa18f31f072c0 R15: ffffda83ffd4be40 FS: 0000000000000000(0000) GS:ffffa0da43b80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000040 CR3: 0000002c77c0a003 CR4: 00000000007626e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: ksm_scan_thread+0x115e/0x1960 kthread+0xf5/0x130 ret_from_fork+0x1f/0x30 [songmuchun@bytedance.com: if the vma is out of date, just exit] Link: http://lkml.kernel.org/r/20200416025034.29780-1-songmuchun@bytedance.com [akpm@linux-foundation.org: add the conventional braces, replace /** with /*] Fixes: e86c59b1b12d ("mm/ksm: improve deduplication of zero pages with colouring") Co-developed-by: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Hugh Dickins <hughd@google.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Cc: Markus Elfring <Markus.Elfring@web.de> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/20200416025034.29780-1-songmuchun@bytedance.com Link: http://lkml.kernel.org/r/20200414132905.83819-1-songmuchun@bytedance.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07mm: use fallthrough;Joe Perches
Convert the various /* fallthrough */ comments to the pseudo-keyword fallthrough; Done via script: https://lore.kernel.org/lkml/b56602fcf79f849e733e7b521bb0e17895d390fa.1582230379.git.joe@perches.com/ Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Link: http://lkml.kernel.org/r/f62fea5d10eb0ccfc05d87c242a620c261219b66.camel@perches.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07mm/ksm.c: update get_user_pages() argument in commentLi Chen
This updates get_user_pages()'s argument in ksm_test_exit()'s comment Signed-off-by: Li Chen <chenli@uniontech.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/30ac2417-f1c7-f337-0beb-df561295298c@uniontech.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-04Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds
Pull more KVM updates from Paolo Bonzini: - PPC secure guest support - small x86 cleanup - fix for an x86-specific out-of-bounds write on a ioctl (not guest triggerable, data not attacker-controlled) * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: kvm: vmx: Stop wasting a page for guest_msrs KVM: x86: fix out-of-bounds write in KVM_GET_EMULATED_CPUID (CVE-2019-19332) Documentation: kvm: Fix mention to number of ioctls classes powerpc: Ultravisor: Add PPC_UV config option KVM: PPC: Book3S HV: Support reset of secure guest KVM: PPC: Book3S HV: Handle memory plug/unplug to secure VM KVM: PPC: Book3S HV: Radix changes for secure guest KVM: PPC: Book3S HV: Shared pages support for secure guests KVM: PPC: Book3S HV: Support for running secure guests mm: ksm: Export ksm_madvise() KVM x86: Move kvm cpuid support out of svm
2019-11-28mm: ksm: Export ksm_madvise()Bharata B Rao
On PEF-enabled POWER platforms that support running of secure guests, secure pages of the guest are represented by device private pages in the host. Such pages needn't participate in KSM merging. This is achieved by using ksm_madvise() call which need to be exported since KVM PPC can be a kernel module. Signed-off-by: Bharata B Rao <bharata@linux.ibm.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
2019-11-22mm/ksm.c: don't WARN if page is still mapped in remove_stable_node()Andrey Ryabinin
It's possible to hit the WARN_ON_ONCE(page_mapped(page)) in remove_stable_node() when it races with __mmput() and squeezes in between ksm_exit() and exit_mmap(). WARNING: CPU: 0 PID: 3295 at mm/ksm.c:888 remove_stable_node+0x10c/0x150 Call Trace: remove_all_stable_nodes+0x12b/0x330 run_store+0x4ef/0x7b0 kernfs_fop_write+0x200/0x420 vfs_write+0x154/0x450 ksys_write+0xf9/0x1d0 do_syscall_64+0x99/0x510 entry_SYSCALL_64_after_hwframe+0x49/0xbe Remove the warning as there is nothing scary going on. Link: http://lkml.kernel.org/r/20191119131850.5675-1-aryabinin@virtuozzo.com Fixes: cbf86cfe04a6 ("ksm: remove old stable nodes more thoroughly") Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-24mm: move memcmp_pages() and pages_identical()Song Liu
Patch series "THP aware uprobe", v13. This patchset makes uprobe aware of THPs. Currently, when uprobe is attached to text on THP, the page is split by FOLL_SPLIT. As a result, uprobe eliminates the performance benefit of THP. This set makes uprobe THP-aware. Instead of FOLL_SPLIT, we introduces FOLL_SPLIT_PMD, which only split PMD for uprobe. After all uprobes within the THP are removed, the PTE-mapped pages are regrouped as huge PMD. This set (plus a few THP patches) is also available at https://github.com/liu-song-6/linux/tree/uprobe-thp This patch (of 6): Move memcmp_pages() to mm/util.c and pages_identical() to mm.h, so that we can use them in other files. Link: http://lkml.kernel.org/r/20190815164525.1848545-2-songliubraving@fb.com Signed-off-by: Song Liu <songliubraving@fb.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <matthew.wilcox@oracle.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-06-19treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 482Thomas Gleixner
Based on 1 normalized pattern(s): this work is licensed under the terms of the gnu gpl version 2 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 48 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Enrico Weigelt <info@metux.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081204.624030236@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-14mm/mmu_notifier: use correct mmu_notifier events for each invalidationJérôme Glisse
This updates each existing invalidation to use the correct mmu notifier event that represent what is happening to the CPU page table. See the patch which introduced the events to see the rational behind this. Link: http://lkml.kernel.org/r/20190326164747.24405-7-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Cc: Christian König <christian.koenig@amd.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Peter Xu <peterx@redhat.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Ross Zwisler <zwisler@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krcmar <rkrcmar@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christian Koenig <christian.koenig@amd.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14mm/mmu_notifier: contextual information for event triggering invalidationJérôme Glisse
CPU page table update can happens for many reasons, not only as a result of a syscall (munmap(), mprotect(), mremap(), madvise(), ...) but also as a result of kernel activities (memory compression, reclaim, migration, ...). Users of mmu notifier API track changes to the CPU page table and take specific action for them. While current API only provide range of virtual address affected by the change, not why the changes is happening. This patchset do the initial mechanical convertion of all the places that calls mmu_notifier_range_init to also provide the default MMU_NOTIFY_UNMAP event as well as the vma if it is know (most invalidation happens against a given vma). Passing down the vma allows the users of mmu notifier to inspect the new vma page protection. The MMU_NOTIFY_UNMAP is always the safe default as users of mmu notifier should assume that every for the range is going away when that event happens. A latter patch do convert mm call path to use a more appropriate events for each call. This is done as 2 patches so that no call site is forgotten especialy as it uses this following coccinelle patch: %<---------------------------------------------------------------------- @@ identifier I1, I2, I3, I4; @@ static inline void mmu_notifier_range_init(struct mmu_notifier_range *I1, +enum mmu_notifier_event event, +unsigned flags, +struct vm_area_struct *vma, struct mm_struct *I2, unsigned long I3, unsigned long I4) { ... } @@ @@ -#define mmu_notifier_range_init(range, mm, start, end) +#define mmu_notifier_range_init(range, event, flags, vma, mm, start, end) @@ expression E1, E3, E4; identifier I1; @@ <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, I1, I1->vm_mm, E3, E4) ...> @@ expression E1, E2, E3, E4; identifier FN, VMA; @@ FN(..., struct vm_area_struct *VMA, ...) { <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, VMA, E2, E3, E4) ...> } @@ expression E1, E2, E3, E4; identifier FN, VMA; @@ FN(...) { struct vm_area_struct *VMA; <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, VMA, E2, E3, E4) ...> } @@ expression E1, E2, E3, E4; identifier FN; @@ FN(...) { <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, NULL, E2, E3, E4) ...> } ---------------------------------------------------------------------->% Applied with: spatch --all-includes --sp-file mmu-notifier.spatch fs/proc/task_mmu.c --in-place spatch --sp-file mmu-notifier.spatch --dir kernel/events/ --in-place spatch --sp-file mmu-notifier.spatch --dir mm --in-place Link: http://lkml.kernel.org/r/20190326164747.24405-6-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Cc: Christian König <christian.koenig@amd.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Peter Xu <peterx@redhat.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Ross Zwisler <zwisler@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krcmar <rkrcmar@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christian Koenig <christian.koenig@amd.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-05mm: ksm: do not block on page lock when searching stable treeYang Shi
ksmd needs to search the stable tree to look for the suitable KSM page, but the KSM page might be locked for a while due to i.e. KSM page rmap walk. Basically it is not a big deal since commit 2c653d0ee2ae ("ksm: introduce ksm_max_page_sharing per page deduplication limit"), since max_page_sharing limits the number of shared KSM pages. But it still sounds not worth waiting for the lock, the page can be skip, then try to merge it in the next scan to avoid potential stall if its content is still intact. Introduce trylock mode to get_ksm_page() to not block on page lock, like what try_to_merge_one_page() does. And, define three possible operations (nolock, lock and trylock) as enum type to avoid stacking up bools and make the code more readable. Return -EBUSY if trylock fails, since NULL means not find suitable KSM page, which is a valid case. With the default max_page_sharing setting (256), there is almost no observed change comparing lock vs trylock. However, with ksm02 of LTP, the reduced ksmd full scan time can be observed, which has set max_page_sharing to 786432. With lock version, ksmd may tak 10s - 11s to run two full scans, with trylock version ksmd may take 8s - 11s to run two full scans. And, the number of pages_sharing and pages_to_scan keep same. Basically, this change has no harm. [hughd@google.com: fix BUG_ON()] Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1902182122280.6914@eggly.anvils Link: http://lkml.kernel.org/r/1548793753-62377-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Hugh Dickins <hughd@google.com> Suggested-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-05mm: reuse only-pte-mapped KSM page in do_wp_page()Kirill Tkhai
Add an optimization for KSM pages almost in the same way that we have for ordinary anonymous pages. If there is a write fault in a page, which is mapped to an only pte, and it is not related to swap cache; the page may be reused without copying its content. [ Note that we do not consider PageSwapCache() pages at least for now, since we don't want to complicate __get_ksm_page(), which has nice optimization based on this (for the migration case). Currenly it is spinning on PageSwapCache() pages, waiting for when they have unfreezed counters (i.e., for the migration finish). But we don't want to make it also spinning on swap cache pages, which we try to reuse, since there is not a very high probability to reuse them. So, for now we do not consider PageSwapCache() pages at all. ] So in reuse_ksm_page() we check for 1) PageSwapCache() and 2) page_stable_node(), to skip a page, which KSM is currently trying to link to stable tree. Then we do page_ref_freeze() to prohibit KSM to merge one more page into the page, we are reusing. After that, nobody can refer to the reusing page: KSM skips !PageSwapCache() pages with zero refcount; and the protection against of all other participants is the same as for reused ordinary anon pages pte lock, page lock and mmap_sem. [akpm@linux-foundation.org: replace BUG_ON()s with WARN_ON()s] Link: http://lkml.kernel.org/r/154471491016.31352.1168978849911555609.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Koenig <christian.koenig@amd.com> Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Cc: Rik van Riel <riel@surriel.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-05mm: replace all open encodings for NUMA_NO_NODEAnshuman Khandual
Patch series "Replace all open encodings for NUMA_NO_NODE", v3. All these places for replacement were found by running the following grep patterns on the entire kernel code. Please let me know if this might have missed some instances. This might also have replaced some false positives. I will appreciate suggestions, inputs and review. 1. git grep "nid == -1" 2. git grep "node == -1" 3. git grep "nid = -1" 4. git grep "node = -1" This patch (of 2): At present there are multiple places where invalid node number is encoded as -1. Even though implicitly understood it is always better to have macros in there. Replace these open encodings for an invalid node number with the global macro NUMA_NO_NODE. This helps remove NUMA related assumptions like 'invalid node' from various places redirecting them to a common definition. Link: http://lkml.kernel.org/r/1545127933-10711-2-git-send-email-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> [ixgbe] Acked-by: Jens Axboe <axboe@kernel.dk> [mtip32xx] Acked-by: Vinod Koul <vkoul@kernel.org> [dmaengine.c] Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc] Acked-by: Doug Ledford <dledford@redhat.com> [drivers/infiniband] Cc: Joseph Qi <jiangqi903@gmail.com> Cc: Hans Verkuil <hverkuil@xs4all.nl> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28ksm: react on changing "sleep_millisecs" parameter fasterKirill Tkhai
ksm thread unconditionally sleeps in ksm_scan_thread() after each iteration: schedule_timeout_interruptible( msecs_to_jiffies(ksm_thread_sleep_millisecs)) The timeout is configured in /sys/kernel/mm/ksm/sleep_millisecs. In case of user writes a big value by a mistake, and the thread enters into schedule_timeout_interruptible(), it's not possible to cancel the sleep by writing a new smaler value; the thread is just sleeping till timeout expires. The patch fixes the problem by waking the thread each time after the value is updated. This also may be useful for debug purposes; and also for userspace daemons, which change sleep_millisecs value in dependence of system load. Link: http://lkml.kernel.org/r/154454107680.3258.3558002210423531566.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Cyrill Gorcunov <gorcunov@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28mm/mmu_notifier: use structure for invalidate_range_start/end calls v2Jérôme Glisse
To avoid having to change many call sites everytime we want to add a parameter use a structure to group all parameters for the mmu_notifier invalidate_range_start/end cakks. No functional changes with this patch. [akpm@linux-foundation.org: coding style fixes] Link: http://lkml.kernel.org/r/20181205053628.3210-3-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Acked-by: Christian König <christian.koenig@amd.com> Acked-by: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Ross Zwisler <zwisler@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krcmar <rkrcmar@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Felix Kuehling <felix.kuehling@amd.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> From: Jérôme Glisse <jglisse@redhat.com> Subject: mm/mmu_notifier: use structure for invalidate_range_start/end calls v3 fix build warning in migrate.c when CONFIG_MMU_NOTIFIER=n Link: http://lkml.kernel.org/r/20181213171330.8489-3-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28ksm: replace jhash2 with xxhashTimofey Titovets
Replace jhash2 with xxhash. Perf numbers: Intel(R) Xeon(R) CPU E5-2420 v2 @ 2.20GHz ksm: crc32c hash() 12081 MB/s ksm: xxh64 hash() 8770 MB/s ksm: xxh32 hash() 4529 MB/s ksm: jhash2 hash() 1569 MB/s Sioh Lee did some testing: crc32c_intel: 1084.10ns crc32c (no hardware acceleration): 7012.51ns xxhash32: 2227.75ns xxhash64: 1413.16ns jhash2: 5128.30ns As jhash2 always will be slower (for data size like PAGE_SIZE). Don't use it in ksm at all. Use only xxhash for now, because for using crc32c, cryptoapi must be initialized first - that requires some tricky solution to work well in all situations. Link: http://lkml.kernel.org/r/20181023182554.23464-3-nefelim4ag@gmail.com Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com> Signed-off-by: leesioh <solee@os.korea.ac.kr> Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22include/linux/compiler*.h: make compiler-*.h mutually exclusiveNick Desaulniers
Commit cafa0010cd51 ("Raise the minimum required gcc version to 4.6") recently exposed a brittle part of the build for supporting non-gcc compilers. Both Clang and ICC define __GNUC__, __GNUC_MINOR__, and __GNUC_PATCHLEVEL__ for quick compatibility with code bases that haven't added compiler specific checks for __clang__ or __INTEL_COMPILER. This is brittle, as they happened to get compatibility by posing as a certain version of GCC. This broke when upgrading the minimal version of GCC required to build the kernel, to a version above what ICC and Clang claim to be. Rather than always including compiler-gcc.h then undefining or redefining macros in compiler-intel.h or compiler-clang.h, let's separate out the compiler specific macro definitions into mutually exclusive headers, do more proper compiler detection, and keep shared definitions in compiler_types.h. Fixes: cafa0010cd51 ("Raise the minimum required gcc version to 4.6") Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com> Suggested-by: Eli Friedman <efriedma@codeaurora.org> Suggested-by: Joe Perches <joe@perches.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22mm: fix page_freeze_refs and page_unfreeze_refs in commentsJiang Biao
page_freeze_refs/page_unfreeze_refs have already been relplaced by page_ref_freeze/page_ref_unfreeze , but they are not modified in the comments. Link: http://lkml.kernel.org/r/1532590226-106038-1-git-send-email-jiang.biao2@zte.com.cn Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-17mm: convert return type of handle_mm_fault() caller to vm_fault_tSouptick Joarder
Use new return type vm_fault_t for fault handler. For now, this is just documenting that the function returns a VM_FAULT value rather than an errno. Once all instances are converted, vm_fault_t will become a distinct type. Ref-> commit 1c8f422059ae ("mm: change return type to vm_fault_t") In this patch all the caller of handle_mm_fault() are changed to return vm_fault_t type. Link: http://lkml.kernel.org/r/20180617084810.GA6730@jordon-HP-15-Notebook-PC Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Tony Luck <tony.luck@intel.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Michal Simek <monstr@monstr.eu> Cc: James Hogan <jhogan@kernel.org> Cc: Ley Foon Tan <lftan@altera.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: James E.J. Bottomley <jejb@parisc-linux.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: David S. Miller <davem@davemloft.net> Cc: Richard Weinberger <richard@nod.at> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-17dax: remove VM_MIXEDMAP for fsdax and device daxDave Jiang
This patch is reworked from an earlier patch that Dan has posted: https://patchwork.kernel.org/patch/10131727/ VM_MIXEDMAP is used by dax to direct mm paths like vm_normal_page() that the memory page it is dealing with is not typical memory from the linear map. The get_user_pages_fast() path, since it does not resolve the vma, is already using {pte,pmd}_devmap() as a stand-in for VM_MIXEDMAP, so we use that as a VM_MIXEDMAP replacement in some locations. In the cases where there is no pte to consult we fallback to using vma_is_dax() to detect the VM_MIXEDMAP special case. Now that we have explicit driver pfn_t-flag opt-in/opt-out for get_user_pages() support for DAX we can stop setting VM_MIXEDMAP. This also means we no longer need to worry about safely manipulating vm_flags in a future where we support dynamically changing the dax mode of a file. DAX should also now be supported with madvise_behavior(), vma_merge(), and copy_page_range(). This patch has been tested against ndctl unit test. It has also been tested against xfstests commit: 625515d using fake pmem created by memmap and no additional issues have been observed. Link: http://lkml.kernel.org/r/152847720311.55924.16999195879201817653.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Dave Jiang <dave.jiang@intel.com> Acked-by: Dan Williams <dan.j.williams@intel.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-15mm/ksm.c: ignore STABLE_FLAG of rmap_item->address in rmap_walk_ksm()Jia He
In our armv8a server(QDF2400), I noticed lots of WARN_ON caused by PAGE_SIZE unaligned for rmap_item->address under memory pressure tests(start 20 guests and run memhog in the host). WARNING: CPU: 4 PID: 4641 at virt/kvm/arm/mmu.c:1826 kvm_age_hva_handler+0xc0/0xc8 CPU: 4 PID: 4641 Comm: memhog Tainted: G W 4.17.0-rc3+ #8 Call trace: kvm_age_hva_handler+0xc0/0xc8 handle_hva_to_gpa+0xa8/0xe0 kvm_age_hva+0x4c/0xe8 kvm_mmu_notifier_clear_flush_young+0x54/0x98 __mmu_notifier_clear_flush_young+0x6c/0xa0 page_referenced_one+0x154/0x1d8 rmap_walk_ksm+0x12c/0x1d0 rmap_walk+0x94/0xa0 page_referenced+0x194/0x1b0 shrink_page_list+0x674/0xc28 shrink_inactive_list+0x26c/0x5b8 shrink_node_memcg+0x35c/0x620 shrink_node+0x100/0x430 do_try_to_free_pages+0xe0/0x3a8 try_to_free_pages+0xe4/0x230 __alloc_pages_nodemask+0x564/0xdc0 alloc_pages_vma+0x90/0x228 do_anonymous_page+0xc8/0x4d0 __handle_mm_fault+0x4a0/0x508 handle_mm_fault+0xf8/0x1b0 do_page_fault+0x218/0x4b8 do_translation_fault+0x90/0xa0 do_mem_abort+0x68/0xf0 el0_da+0x24/0x28 In rmap_walk_ksm, the rmap_item->address might still have the STABLE_FLAG, then the start and end in handle_hva_to_gpa might not be PAGE_SIZE aligned. Thus it will cause exceptions in handle_hva_to_gpa on arm64. This patch fixes it by ignoring (not removing) the low bits of address when doing rmap_walk_ksm. IMO, it should be backported to stable tree. the storm of WARN_ONs is very easy for me to reproduce. More than that, I watched a panic (not reproducible) as follows: page:ffff7fe003742d80 count:-4871 mapcount:-2126053375 mapping: (null) index:0x0 flags: 0x1fffc00000000000() raw: 1fffc00000000000 0000000000000000 0000000000000000 ffffecf981470000 raw: dead000000000100 dead000000000200 ffff8017c001c000 0000000000000000 page dumped because: nonzero _refcount CPU: 29 PID: 18323 Comm: qemu-kvm Tainted: G W 4.14.15-5.hxt.aarch64 #1 Hardware name: <snip for confidential issues> Call trace: dump_backtrace+0x0/0x22c show_stack+0x24/0x2c dump_stack+0x8c/0xb0 bad_page+0xf4/0x154 free_pages_check_bad+0x90/0x9c free_pcppages_bulk+0x464/0x518 free_hot_cold_page+0x22c/0x300 __put_page+0x54/0x60 unmap_stage2_range+0x170/0x2b4 kvm_unmap_hva_handler+0x30/0x40 handle_hva_to_gpa+0xb0/0xec kvm_unmap_hva_range+0x5c/0xd0 I even injected a fault on purpose in kvm_unmap_hva_range by seting size=size-0x200, the call trace is similar as above. So I thought the panic is similarly caused by the root cause of WARN_ON. Andrea said: : It looks a straightforward safe fix, on x86 hva_to_gfn_memslot would : zap those bits and hide the misalignment caused by the low metadata : bits being erroneously left set in the address, but the arm code : notices when that's the last page in the memslot and the hva_end is : getting aligned and the size is below one page. : : I think the problem triggers in the addr += PAGE_SIZE of : unmap_stage2_ptes that never matches end because end is aligned but : addr is not. : : } while (pte++, addr += PAGE_SIZE, addr != end); : : x86 again only works on hva_start/hva_end after converting it to : gfn_start/end and that being in pfn units the bits are zapped before : they risk to cause trouble. Jia He said: : I've tested by myself in arm64 server (QDF2400,46 cpus,96G mem) Without : this patch, the WARN_ON is very easy for reproducing. After this patch, I : have run the same benchmarch for a whole day without any WARN_ONs Link: http://lkml.kernel.org/r/1525403506-6750-1-git-send-email-hejianet@gmail.com Signed-off-by: Jia He <jia.he@hxt-semitech.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Tested-by: Jia He <hejianet@gmail.com> Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Cc: Arvind Yadav <arvind.yadav.cs@gmail.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-07mm/ksm: move [set_]page_stable_node from ksm.h to ksm.cMike Rapoport
page_stable_node() and set_page_stable_node() are only used in mm/ksm.c and there is no point to keep them in the include/linux/ksm.h [akpm@linux-foundation.org: fix SYSFS=n build] Link: http://lkml.kernel.org/r/1524552106-7356-3-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-27mm/ksm: docs: extend overview comment and make it "DOC:"Mike Rapoport
The existing comment provides a good overview of KSM implementation. Let's update it to reflect recent additions of "chain" and "dup" variants of the stable tree nodes and mark it as "DOC:" for inclusion into the KSM documentation. Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-04-16Merge branch 'mm-rst' into docs-nextJonathan Corbet
Mike Rapoport says: These patches convert files in Documentation/vm to ReST format, add an initial index and link it to the top level documentation. There are no contents changes in the documentation, except few spelling fixes. The relatively large diffstat stems from the indentation and paragraph wrapping changes. I've tried to keep the formatting as consistent as possible, but I could miss some places that needed markup and add some markup where it was not necessary. [jc: significant conflicts in vm/hmm.rst]
2018-04-16docs/vm: rename documentation files to .rstMike Rapoport
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-04-11mm/ksm.c: fix inconsistent accounting of zero pagesClaudio Imbrenda
When using KSM with use_zero_pages, we replace anonymous pages containing only zeroes with actual zero pages, which are not anonymous. We need to do proper accounting of the mm counters, otherwise we will get wrong values in /proc and a BUG message in dmesg when tearing down the mm. Link: http://lkml.kernel.org/r/1522931274-15552-1-git-send-email-imbrenda@linux.vnet.ibm.com Fixes: e86c59b1b1 ("mm/ksm: improve deduplication of zero pages with colouring") Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-05mm/ksm: fix interaction with THPClaudio Imbrenda
This patch fixes a corner case for KSM. When two pages belong or belonged to the same transparent hugepage, and they should be merged, KSM fails to split the page, and therefore no merging happens. This bug can be reproduced by: * making sure ksm is running (in case disabling ksmtuned) * enabling transparent hugepages * allocating a THP-aligned 1-THP-sized buffer e.g. on amd64: posix_memalign(&p, 1<<21, 1<<21) * filling it with the same values e.g. memset(p, 42, 1<<21) * performing madvise to make it mergeable e.g. madvise(p, 1<<21, MADV_MERGEABLE) * waiting for KSM to perform a few scans The expected outcome is that the all the pages get merged (1 shared and the rest sharing); the actual outcome is that no pages get merged (1 unshared and the rest volatile) The reason of this behaviour is that we increase the reference count once for both pages we want to merge, but if they belong to the same hugepage (or compound page), the reference counter used in both cases is the one of the head of the compound page. This means that split_huge_page will find a value of the reference counter too high and will fail. This patch solves this problem by testing if the two pages to merge belong to the same hugepage when attempting to merge them. If so, the hugepage is split safely. This means that the hugepage is not split if not necessary. Link: http://lkml.kernel.org/r/1521548069-24758-1-git-send-email-imbrenda@linux.vnet.ibm.com Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Co-authored-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-05mm/ksm.c: make stable_node_dup() staticColin Ian King
stable_node_dup() is local to the source and does not need to be in global scope, so make it static. Cleans up sparse warning: mm/ksm.c:1321:13: warning: symbol 'stable_node_dup' was not declared. Should it be static? Link: http://lkml.kernel.org/r/20180206221005.12642-1-colin.king@canonical.com Signed-off-by: Colin Ian King <colin.king@canonical.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-03-18sparc64: Add support for ADI (Application Data Integrity)Khalid Aziz
ADI is a new feature supported on SPARC M7 and newer processors to allow hardware to catch rogue accesses to memory. ADI is supported for data fetches only and not instruction fetches. An app can enable ADI on its data pages, set version tags on them and use versioned addresses to access the data pages. Upper bits of the address contain the version tag. On M7 processors, upper four bits (bits 63-60) contain the version tag. If a rogue app attempts to access ADI enabled data pages, its access is blocked and processor generates an exception. Please see Documentation/sparc/adi.txt for further details. This patch extends mprotect to enable ADI (TSTATE.mcde), enable/disable MCD (Memory Corruption Detection) on selected memory ranges, enable TTE.mcd in PTEs, return ADI parameters to userspace and save/restore ADI version tags on page swap out/in or migration. ADI is not enabled by default for any task. A task must explicitly enable ADI on a memory range and set version tag for ADI to be effective for the task. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Khalid Aziz <khalid@gonehiking.org> Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-02-06mm: docs: fixup punctuationMike Rapoport
so that kernel-doc will properly recognize the parameter and function descriptions. Link: http://lkml.kernel.org/r/1516700871-22279-2-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-12-04mm/ksm: Remove now-redundant smp_read_barrier_depends()Paul E. McKenney
Because READ_ONCE() now implies smp_read_barrier_depends(), the smp_read_barrier_depends() in get_ksm_page() is now redundant. This commit removes it and updates the comments. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Cc: <linux-mm@kvack.org>
2017-11-15mm/mmu_notifier: avoid double notification when it is uselessJérôme Glisse
This patch only affects users of mmu_notifier->invalidate_range callback which are device drivers related to ATS/PASID, CAPI, IOMMUv2, SVM ... and it is an optimization for those users. Everyone else is unaffected by it. When clearing a pte/pmd we are given a choice to notify the event under the page table lock (notify version of *_clear_flush helpers do call the mmu_notifier_invalidate_range). But that notification is not necessary in all cases. This patch removes almost all cases where it is useless to have a call to mmu_notifier_invalidate_range before mmu_notifier_invalidate_range_end. It also adds documentation in all those cases explaining why. Below is a more in depth analysis of why this is fine to do this: For secondary TLB (non CPU TLB) like IOMMU TLB or device TLB (when device use thing like ATS/PASID to get the IOMMU to walk the CPU page table to access a process virtual address space). There is only 2 cases when you need to notify those secondary TLB while holding page table lock when clearing a pte/pmd: A) page backing address is free before mmu_notifier_invalidate_range_end B) a page table entry is updated to point to a new page (COW, write fault on zero page, __replace_page(), ...) Case A is obvious you do not want to take the risk for the device to write to a page that might now be used by something completely different. Case B is more subtle. For correctness it requires the following sequence to happen: - take page table lock - clear page table entry and notify (pmd/pte_huge_clear_flush_notify()) - set page table entry to point to new page If clearing the page table entry is not followed by a notify before setting the new pte/pmd value then you can break memory model like C11 or C++11 for the device. Consider the following scenario (device use a feature similar to ATS/ PASID): Two address addrA and addrB such that |addrA - addrB| >= PAGE_SIZE we assume they are write protected for COW (other case of B apply too). [Time N] ----------------------------------------------------------------- CPU-thread-0 {try to write to addrA} CPU-thread-1 {try to write to addrB} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {read addrA and populate device TLB} DEV-thread-2 {read addrB and populate device TLB} [Time N+1] --------------------------------------------------------------- CPU-thread-0 {COW_step0: {mmu_notifier_invalidate_range_start(addrA)}} CPU-thread-1 {COW_step0: {mmu_notifier_invalidate_range_start(addrB)}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+2] --------------------------------------------------------------- CPU-thread-0 {COW_step1: {update page table point to new page for addrA}} CPU-thread-1 {COW_step1: {update page table point to new page for addrB}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+3] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {preempted} CPU-thread-2 {write to addrA which is a write to new page} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+3] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {preempted} CPU-thread-2 {} CPU-thread-3 {write to addrB which is a write to new page} DEV-thread-0 {} DEV-thread-2 {} [Time N+4] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {COW_step3: {mmu_notifier_invalidate_range_end(addrB)}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+5] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {read addrA from old page} DEV-thread-2 {read addrB from new page} So here because at time N+2 the clear page table entry was not pair with a notification to invalidate the secondary TLB, the device see the new value for addrB before seing the new value for addrA. This break total memory ordering for the device. When changing a pte to write protect or to point to a new write protected page with same content (KSM) it is ok to delay invalidate_range callback to mmu_notifier_invalidate_range_end() outside the page table lock. This is true even if the thread doing page table update is preempted right after releasing page table lock before calling mmu_notifier_invalidate_range_end Thanks to Andrea for thinking of a problematic scenario for COW. [jglisse@redhat.com: v2] Link: http://lkml.kernel.org/r/20171017031003.7481-2-jglisse@redhat.com Link: http://lkml.kernel.org/r/20170901173011.10745-1-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Alistair Popple <alistair@popple.id.au> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-10-03ksm: fix unlocked iteration over vmas in cmp_and_merge_page()Kirill Tkhai
In this place mm is unlocked, so vmas or list may change. Down read mmap_sem to protect them from modifications. Link: http://lkml.kernel.org/r/150512788393.10691.8868381099691121308.stgit@localhost.localdomain Fixes: e86c59b1b12d ("mm/ksm: improve deduplication of zero pages with colouring") Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: zhong jiang <zhongjiang@huawei.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-06mm/ksm.c: constify attribute_group structuresArvind Yadav
attribute_group are not supposed to change at runtime. All functions working with attribute_group provided by <linux/sysfs.h> work with const attribute_group. So mark the non-const structs as const. Link: http://lkml.kernel.org/r/1501157167-3706-2-git-send-email-arvind.yadav.cs@gmail.com Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-10mm: fix KSM data corruptionMinchan Kim
Nadav reported KSM can corrupt the user data by the TLB batching race[1]. That means data user written can be lost. Quote from Nadav Amit: "For this race we need 4 CPUs: CPU0: Caches a writable and dirty PTE entry, and uses the stale value for write later. CPU1: Runs madvise_free on the range that includes the PTE. It would clear the dirty-bit. It batches TLB flushes. CPU2: Writes 4 to /proc/PID/clear_refs , clearing the PTEs soft-dirty. We care about the fact that it clears the PTE write-bit, and of course, batches TLB flushes. CPU3: Runs KSM. Our purpose is to pass the following test in write_protect_page(): if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte) || (pte_protnone(*pvmw.pte) && pte_savedwrite(*pvmw.pte))) Since it will avoid TLB flush. And we want to do it while the PTE is stale. Later, and before replacing the page, we would be able to change the page. Note that all the operations the CPU1-3 perform canhappen in parallel since they only acquire mmap_sem for read. We start with two identical pages. Everything below regards the same page/PTE. CPU0 CPU1 CPU2 CPU3 ---- ---- ---- ---- Write the same value on page [cache PTE as dirty in TLB] MADV_FREE pte_mkclean() 4 > clear_refs pte_wrprotect() write_protect_page() [ success, no flush ] pages_indentical() [ ok ] Write to page different value [Ok, using stale PTE] replace_page() Later, CPU1, CPU2 and CPU3 would flush the TLB, but that is too late. CPU0 already wrote on the page, but KSM ignored this write, and it got lost" In above scenario, MADV_FREE is fixed by changing TLB batching API including [set|clear]_tlb_flush_pending. Remained thing is soft-dirty part. This patch changes soft-dirty uses TLB batching API instead of flush_tlb_mm and KSM checks pending TLB flush by using mm_tlb_flush_pending so that it will flush TLB to avoid data lost if there are other parallel threads pending TLB flush. [1] http://lkml.kernel.org/r/BD3A0EBE-ECF4-41D4-87FA-C755EA9AB6BD@gmail.com Link: http://lkml.kernel.org/r/20170802000818.4760-8-namit@vmware.com Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Nadav Amit <namit@vmware.com> Reported-by: Nadav Amit <namit@vmware.com> Tested-by: Nadav Amit <namit@vmware.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Hugh Dickins <hughd@google.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06ksm: optimize refile of stable_node_dup at the head of the chainAndrea Arcangeli
If a candidate stable_node_dup has been found and it can accept further merges it can be refiled to the head of the list to speedup next searches without altering which dup is found and how the dups accumulate in the chain. We already refiled it back to the head in the prune_stale_stable_nodes case, but we didn't refile it if not pruning (which is more common). And we also refiled it when it was already at the head which is unnecessary (in the prune_stale_stable_nodes case, nr > 1 means there's more than one dup in the chain, it doesn't mean it's not already at the head of the chain). The stable_node_chain list is single threaded and there's no SMP locking contention so it should be faster to refile it to the head of the list also if prune_stale_stable_nodes is false. Profiling shows the refile happens 1.9% of the time when a dup is found with a max_page_sharing limit setting of 3 (with max_page_sharing of 2 the refile never happens of course as there's never space for one more merge) which is reasonably low. At higher max_page_sharing values it should be much less frequent. This is just an optimization. Link: http://lkml.kernel.org/r/20170518173721.22316-4-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Evgheni Dereveanchin <ederevea@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Gavin Guo <gavin.guo@canonical.com> Cc: Jay Vosburgh <jay.vosburgh@canonical.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06ksm: swap the two output parameters of chain/chain_pruneAndrea Arcangeli
Some static checker complains if chain/chain_prune returns a potentially stale pointer. There are two output parameters to chain/chain_prune, one is tree_page the other is stable_node_dup. Like in get_ksm_page the caller has to check tree_page is NULL before touching the stable_node. Similarly in chain/chain_prune the caller has to check tree_page before touching the stable_node_dup returned or the original stable_node passed as parameter. Because the tree_page is never returned as a stale pointer, it may be more intuitive to return tree_page and to pass stable_node_dup for reference instead of the reverse. This patch purely swaps the two output parameters of chain/chain_prune as a cleanup for the static checker and to mimic the get_ksm_page behavior more closely. There's no change to the caller at all except the swap, it's purely a cleanup and it is a noop from the caller point of view. Link: http://lkml.kernel.org/r/20170518173721.22316-3-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Tested-by: Dan Carpenter <dan.carpenter@oracle.com> Cc: Evgheni Dereveanchin <ederevea@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Gavin Guo <gavin.guo@canonical.com> Cc: Jay Vosburgh <jay.vosburgh@canonical.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06ksm: cleanup stable_node chain collapse caseAndrea Arcangeli
Patch series "KSMscale cleanup/optimizations". There are no fixes here it's just minor cleanups and optimizations. 1/3 removes makes the "fix" for the stale stable_node fall in the standard case without introducing new cases. Setting stable_node to NULL was marginally safer, but stale pointer is still wiped from the caller, this looks cleaner. 2/3 should fix the false positive from Dan's static checker. 3/3 is a microoptimization to apply the the refile of future merge candidate dups at the head of the chain in all cases and to skip it in one case where we did it and but it was a noop (to avoid checking if it was already at the head but now we've to check it anyway so it got optimized away). This patch (of 3): When the stable_node chain is collapsed we can as well set the caller stable_node to match the returned stable_node_dup in chain_prune(). This way the collapse case becomes indistinguishable from the regular stable_node case and we can remove two branches from the KSM page migration handling slow paths. While it was all correct this looks cleaner (and faster) as the caller has to deal with fewer special cases. Link: http://lkml.kernel.org/r/20170518173721.22316-2-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Evgheni Dereveanchin <ederevea@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Gavin Guo <gavin.guo@canonical.com> Cc: Jay Vosburgh <jay.vosburgh@canonical.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06ksm: fix use after free with merge_across_nodes = 0Andrea Arcangeli
If merge_across_nodes was manually set to 0 (not the default value) by the admin or a tuned profile on NUMA systems triggering cross-NODE page migrations, a stable_node use after free could materialize. If the chain is collapsed stable_node would point to the old chain that was already freed. stable_node_dup would be the stable_node dup now converted to a regular stable_node and indexed in the rbtree in replacement of the freed stable_node chain (not anymore a dup). This special case where the chain is collapsed in the NUMA replacement path, is now detected by setting stable_node to NULL by the chain_prune callee if it decides to collapse the chain. This tells the NUMA replacement code that even if stable_node and stable_node_dup are different, this is not a chain if stable_node is NULL, as the stable_node_dup was converted to a regular stable_node and the chain was collapsed. It is generally safer for the callee to force the caller stable_node to NULL the moment it become stale so any other mistake like this would result in an instant Oops easier to debug than an use after free. Otherwise the replace logic would act like if stable_node was a valid chain, when in fact it was freed. Notably stable_node_chain_add_dup(page_node, stable_node) would run on a stable stable_node. Andrey Ryabinin found the source of the use after free in chain_prune(). Link: http://lkml.kernel.org/r/20170512193805.8807-2-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reported-by: Evgheni Dereveanchin <ederevea@redhat.com> Tested-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Gavin Guo <gavin.guo@canonical.com> Cc: Jay Vosburgh <jay.vosburgh@canonical.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06ksm: introduce ksm_max_page_sharing per page deduplication limitAndrea Arcangeli
Without a max deduplication limit for each KSM page, the list of the rmap_items associated to each stable_node can grow infinitely large. During the rmap walk each entry can take up to ~10usec to process because of IPIs for the TLB flushing (both for the primary MMU and the secondary MMUs with the MMU notifier). With only 16GB of address space shared in the same KSM page, that would amount to dozens of seconds of kernel runtime. A ~256 max deduplication factor will reduce the latencies of the rmap walks on KSM pages to order of a few msec. Just doing the cond_resched() during the rmap walks is not enough, the list size must have a limit too, otherwise the caller could get blocked in (schedule friendly) kernel computations for seconds, unexpectedly. There's room for optimization to significantly reduce the IPI delivery cost during the page_referenced(), but at least for page_migration in the KSM case (used by hard NUMA bindings, compaction and NUMA balancing) it may be inevitable to send lots of IPIs if each rmap_item->mm is active on a different CPU and there are lots of CPUs. Even if we ignore the IPI delivery cost, we've still to walk the whole KSM rmap list, so we can't allow millions or billions (ulimited) number of entries in the KSM stable_node rmap_item lists. The limit is enforced efficiently by adding a second dimension to the stable rbtree. So there are three types of stable_nodes: the regular ones (identical as before, living in the first flat dimension of the stable rbtree), the "chains" and the "dups". Every "chain" and all "dups" linked into a "chain" enforce the invariant that they represent the same write protected memory content, even if each "dup" will be pointed by a different KSM page copy of that content. This way the stable rbtree lookup computational complexity is unaffected if compared to an unlimited max_sharing_limit. It is still enforced that there cannot be KSM page content duplicates in the stable rbtree itself. Adding the second dimension to the stable rbtree only after the max_page_sharing limit hits, provides for a zero memory footprint increase on 64bit archs. The memory overhead of the per-KSM page stable_tree and per virtual mapping rmap_item is unchanged. Only after the max_page_sharing limit hits, we need to allocate a stable_tree "chain" and rb_replace() the "regular" stable_node with the newly allocated stable_node "chain". After that we simply add the "regular" stable_node to the chain as a stable_node "dup" by linking hlist_dup in the stable_node_chain->hlist. This way the "regular" (flat) stable_node is converted to a stable_node "dup" living in the second dimension of the stable rbtree. During stable rbtree lookups the stable_node "chain" is identified as stable_node->rmap_hlist_len == STABLE_NODE_CHAIN (aka is_stable_node_chain()). When dropping stable_nodes, the stable_node "dup" is identified as stable_node->head == STABLE_NODE_DUP_HEAD (aka is_stable_node_dup()). The STABLE_NODE_DUP_HEAD must be an unique valid pointer never used elsewhere in any stable_node->head/node to avoid a clashes with the stable_node->node.rb_parent_color pointer, and different from &migrate_nodes. So the second field of &migrate_nodes is picked and verified as always safe with a BUILD_BUG_ON in case the list_head implementation changes in the future. The STABLE_NODE_DUP is picked as a random negative value in stable_node->rmap_hlist_len. rmap_hlist_len cannot become negative when it's a "regular" stable_node or a stable_node "dup". The stable_node_chain->nid is irrelevant. The stable_node_chain->kpfn is aliased in a union with a time field used to rate limit the stable_node_chain->hlist prunes. The garbage collection of the stable_node_chain happens lazily during stable rbtree lookups (as for all other kind of stable_nodes), or while disabling KSM with "echo 2 >/sys/kernel/mm/ksm/run" while collecting the entire stable rbtree. While the "regular" stable_nodes and the stable_node "dups" must wait for their underlying tree_page to be freed before they can be freed themselves, the stable_node "chains" can be freed immediately if the stable_node->hlist turns empty. This is because the "chains" are never pointed by any page->mapping and they're effectively stable rbtree KSM self contained metadata. [akpm@linux-foundation.org: fix non-NUMA build] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Tested-by: Petr Holasek <pholasek@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Evgheni Dereveanchin <ederevea@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Gavin Guo <gavin.guo@canonical.com> Cc: Jay Vosburgh <jay.vosburgh@canonical.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-02ksm: prevent crash after write_protect_page failsAndrea Arcangeli
"err" needs to be left set to -EFAULT if split_huge_page succeeds. Otherwise if "err" gets clobbered with zero and write_protect_page fails, try_to_merge_one_page() will succeed instead of returning -EFAULT and then try_to_merge_with_ksm_page() will continue thinking kpage is a PageKsm when in fact it's still an anonymous page. Eventually it'll crash in page_add_anon_rmap. This has been reproduced on Fedora25 kernel but I can reproduce with upstream too. The bug was introduced in commit f765f540598a ("ksm: prepare to new THP semantics") introduced in v4.5. page:fffff67546ce1cc0 count:4 mapcount:2 mapping:ffffa094551e36e1 index:0x7f0f46673 flags: 0x2ffffc0004007c(referenced|uptodate|dirty|lru|active|swapbacked) page dumped because: VM_BUG_ON_PAGE(!PageLocked(page)) page->mem_cgroup:ffffa09674bf0000 ------------[ cut here ]------------ kernel BUG at mm/rmap.c:1222! CPU: 1 PID: 76 Comm: ksmd Not tainted 4.9.3-200.fc25.x86_64 #1 RIP: do_page_add_anon_rmap+0x1c4/0x240 Call Trace: page_add_anon_rmap+0x18/0x20 try_to_merge_with_ksm_page+0x50b/0x780 ksm_scan_thread+0x1211/0x1410 ? prepare_to_wait_event+0x100/0x100 ? try_to_merge_with_ksm_page+0x780/0x780 kthread+0xd9/0xf0 ? kthread_park+0x60/0x60 ret_from_fork+0x25/0x30 Fixes: f765f54059 ("ksm: prepare to new THP semantics") Link: http://lkml.kernel.org/r/20170513131040.21732-1-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Federico Simoncelli <fsimonce@redhat.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-03mm: make rmap_one boolean functionMinchan Kim
rmap_one's return value controls whether rmap_work should contine to scan other ptes or not so it's target for changing to boolean. Return true if the scan should be continued. Otherwise, return false to stop the scanning. This patch makes rmap_one's return value to boolean. Link: http://lkml.kernel.org/r/1489555493-14659-10-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-03mm: make rmap_walk() return voidMinchan Kim
There is no user of the return value from rmap_walk() and friends so this patch makes them void-returning functions. Link: http://lkml.kernel.org/r/1489555493-14659-9-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
generated by cgit v1.2.3-58-ga151 (git 2.39.0) at 2024-12-02 22:23:13 +0000