diff options
| author | Laurent Dufour <ldufour@linux.vnet.ibm.com> | 2017-03-09 16:17:06 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-03-09 17:01:10 -0800 |
| commit | bfc7228b9a9647e1c353e50b40297a2929801759 (patch) | |
| tree | 3e7062841c7f20e6d01b871b0705af51a185e89f /mm | |
| parent | f4b7ac68f438fa8521bbbf421f194ff10b0a7577 (diff) | |
mm/cgroup: avoid panic when init with low memory
The system may panic when initialisation is done when almost all the
memory is assigned to the huge pages using the kernel command line
parameter hugepage=xxxx. Panic may occur like this:
Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc000000000302b88
Oops: Kernel access of bad area, sig: 11 [#1]
SMP NR_CPUS=2048 [ 0.082424] NUMA
pSeries
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.9.0-15-generic #16-Ubuntu
task: c00000021ed01600 task.stack: c00000010d108000
NIP: c000000000302b88 LR: c000000000270e04 CTR: c00000000016cfd0
REGS: c00000010d10b2c0 TRAP: 0300 Not tainted (4.9.0-15-generic)
MSR: 8000000002009033 <SF,VEC,EE,ME,IR,DR,RI,LE>[ 0.082770] CR: 28424422 XER: 00000000
CFAR: c0000000003d28b8 DAR: 0000000000000000 DSISR: 40000000 SOFTE: 1
GPR00: c000000000270e04 c00000010d10b540 c00000000141a300 c00000010fff6300
GPR04: 0000000000000000 00000000026012c0 c00000010d10b630 0000000487ab0000
GPR08: 000000010ee90000 c000000001454fd8 0000000000000000 0000000000000000
GPR12: 0000000000004400 c00000000fb80000 00000000026012c0 00000000026012c0
GPR16: 00000000026012c0 0000000000000000 0000000000000000 0000000000000002
GPR20: 000000000000000c 0000000000000000 0000000000000000 00000000024200c0
GPR24: c0000000016eef48 0000000000000000 c00000010fff7d00 00000000026012c0
GPR28: 0000000000000000 c00000010fff7d00 c00000010fff6300 c00000010d10b6d0
NIP mem_cgroup_soft_limit_reclaim+0xf8/0x4f0
LR do_try_to_free_pages+0x1b4/0x450
Call Trace:
do_try_to_free_pages+0x1b4/0x450
try_to_free_pages+0xf8/0x270
__alloc_pages_nodemask+0x7a8/0xff0
new_slab+0x104/0x8e0
___slab_alloc+0x620/0x700
__slab_alloc+0x34/0x60
kmem_cache_alloc_node_trace+0xdc/0x310
mem_cgroup_init+0x158/0x1c8
do_one_initcall+0x68/0x1d0
kernel_init_freeable+0x278/0x360
kernel_init+0x24/0x170
ret_from_kernel_thread+0x5c/0x74
Instruction dump:
eb81ffe0 eba1ffe8 ebc1fff0 ebe1fff8 4e800020 3d230001 e9499a42 3d220004
3929acd8 794a1f24 7d295214 eac90100 <e9360000> 2fa90000 419eff74 3b200000
---[ end trace 342f5208b00d01b6 ]---
This is a chicken and egg issue where the kernel try to get free memory
when allocating per node data in mem_cgroup_init(), but in that path
mem_cgroup_soft_limit_reclaim() is called which assumes that these data
are allocated.
As mem_cgroup_soft_limit_reclaim() is best effort, it should return when
these data are not yet allocated.
This patch also fixes potential null pointer access in
mem_cgroup_remove_from_trees() and mem_cgroup_update_tree().
Link: http://lkml.kernel.org/r/1487856999-16581-2-git-send-email-ldufour@linux.vnet.ibm.com
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memcontrol.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index c52ec893e241..76f513cc1b0e 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -466,6 +466,8 @@ static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page) struct mem_cgroup_tree_per_node *mctz; mctz = soft_limit_tree_from_page(page); + if (!mctz) + return; /* * Necessary to update all ancestors when hierarchy is used. * because their event counter is not touched. @@ -503,7 +505,8 @@ static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg) for_each_node(nid) { mz = mem_cgroup_nodeinfo(memcg, nid); mctz = soft_limit_tree_node(nid); - mem_cgroup_remove_exceeded(mz, mctz); + if (mctz) + mem_cgroup_remove_exceeded(mz, mctz); } } @@ -2558,7 +2561,7 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order, * is empty. Do it lockless to prevent lock bouncing. Races * are acceptable as soft limit is best effort anyway. */ - if (RB_EMPTY_ROOT(&mctz->rb_root)) + if (!mctz || RB_EMPTY_ROOT(&mctz->rb_root)) return 0; /* |