diff options
| author | Ingo Molnar <mingo@kernel.org> | 2017-04-23 11:37:17 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-04-23 11:45:20 +0200 |
| commit | 6dd29b3df975582ef429b5b93c899e6575785940 (patch) | |
| tree | f7f214935c45eb7ea9096fccd4cdace3baa99e68 /mm | |
| parent | ace2fb5a8b65d6aba530068ea9331f18e10ef565 (diff) | |
Revert "x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation"
This reverts commit 2947ba054a4dabbd82848728d765346886050029.
Dan Williams reported dax-pmem kernel warnings with the following signature:
WARNING: CPU: 8 PID: 245 at lib/percpu-refcount.c:155 percpu_ref_switch_to_atomic_rcu+0x1f5/0x200
percpu ref (dax_pmem_percpu_release [dax_pmem]) <= 0 (0) after switching to atomic
... and bisected it to this commit, which suggests possible memory corruption
caused by the x86 fast-GUP conversion.
He also pointed out:
"
This is similar to the backtrace when we were not properly handling
pud faults and was fixed with this commit: 220ced1676c4 "mm: fix
get_user_pages() vs device-dax pud mappings"
I've found some missing _devmap checks in the generic
get_user_pages_fast() path, but this does not fix the regression
[...]
"
So given that there are known bugs, and a pretty robust looking bisection
points to this commit suggesting that are unknown bugs in the conversion
as well, revert it for the time being - we'll re-try in v4.13.
Reported-by: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: dann.frazier@canonical.com
Cc: dave.hansen@intel.com
Cc: steve.capper@linaro.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/Kconfig | 2 | ||||
| -rw-r--r-- | mm/gup.c | 10 |
2 files changed, 6 insertions, 6 deletions
diff --git a/mm/Kconfig b/mm/Kconfig index c89f472b658c..9b8fccb969dc 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -137,7 +137,7 @@ config HAVE_MEMBLOCK_NODE_MAP config HAVE_MEMBLOCK_PHYS_MAP bool -config HAVE_GENERIC_GUP +config HAVE_GENERIC_RCU_GUP bool config ARCH_DISCARD_MEMBLOCK @@ -1155,7 +1155,7 @@ struct page *get_dump_page(unsigned long addr) #endif /* CONFIG_ELF_CORE */ /* - * Generic Fast GUP + * Generic RCU Fast GUP * * get_user_pages_fast attempts to pin user pages by walking the page * tables directly and avoids taking locks. Thus the walker needs to be @@ -1176,8 +1176,8 @@ struct page *get_dump_page(unsigned long addr) * Before activating this code, please be aware that the following assumptions * are currently made: * - * *) Either HAVE_RCU_TABLE_FREE is enabled, and tlb_remove_table() is used to - * free pages containing page tables or TLB flushing requires IPI broadcast. + * *) HAVE_RCU_TABLE_FREE is enabled, and tlb_remove_table is used to free + * pages containing page tables. * * *) ptes can be read atomically by the architecture. * @@ -1187,7 +1187,7 @@ struct page *get_dump_page(unsigned long addr) * * This code is based heavily on the PowerPC implementation by Nick Piggin. */ -#ifdef CONFIG_HAVE_GENERIC_GUP +#ifdef CONFIG_HAVE_GENERIC_RCU_GUP #ifndef gup_get_pte /* @@ -1677,4 +1677,4 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, return ret; } -#endif /* CONFIG_HAVE_GENERIC_GUP */ +#endif /* CONFIG_HAVE_GENERIC_RCU_GUP */ |