[PATCH v2] memcg, oom: don't require __GFP_FS when invoking memcg OOM killer

From: Tetsuo Handa
Date: Mon Aug 05 2019 - 07:28:35 EST

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Masoud Sharbiani noticed that commit 29ef680ae7c21110 ("memcg, oom: move
out_of_memory back to the charge path") broke memcg OOM called from
__xfs_filemap_fault() path. It turned out that try_charge() is retrying
forever without making forward progress because mem_cgroup_oom(GFP_NOFS)
cannot invoke the OOM killer due to commit 3da88fb3bacfaa33 ("mm, oom:
move GFP_NOFS check to out_of_memory").

Allowing forced charge due to being unable to invoke memcg OOM killer
will lead to global OOM situation, and just returning -ENOMEM will not
solve memcg OOM situation. Therefore, invoking memcg OOM killer (despite
GFP_NOFS) will be the only choice we can choose for now.

Until 29ef680ae7c21110~1, we were able to invoke memcg OOM killer when
GFP_KERNEL reclaim failed [1]. But since 29ef680ae7c21110, we need to
invoke memcg OOM killer when GFP_NOFS reclaim failed [2]. Although in
the past we did invoke memcg OOM killer for GFP_NOFS [3], we might get
pre-mature memcg OOM reports due to this patch.

Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Reported-and-tested-by: Masoud Sharbiani <msharbiani@xxxxxxxxx>
Bisected-by: Masoud Sharbiani <msharbiani@xxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Fixes: 3da88fb3bacfaa33 # necessary after 29ef680ae7c21110
Cc: <stable@xxxxxxxxxxxxxxx> # 4.19+

[1]

leaker invoked oom-killer: gfp_mask=0x6200ca(GFP_HIGHUSER_MOVABLE), nodemask=(null), order=0, oom_score_adj=0
CPU: 0 PID: 2746 Comm: leaker Not tainted 4.18.0+ #19
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/13/2018
Call Trace:
dump_stack+0x63/0x88
dump_header+0x67/0x27a
? mem_cgroup_scan_tasks+0x91/0xf0
oom_kill_process+0x210/0x410
out_of_memory+0x10a/0x2c0
mem_cgroup_out_of_memory+0x46/0x80
mem_cgroup_oom_synchronize+0x2e4/0x310
? high_work_func+0x20/0x20
pagefault_out_of_memory+0x31/0x76
mm_fault_error+0x55/0x115
? handle_mm_fault+0xfd/0x220
__do_page_fault+0x433/0x4e0
do_page_fault+0x22/0x30
? page_fault+0x8/0x30
page_fault+0x1e/0x30
RIP: 0033:0x4009f0
Code: 03 00 00 00 e8 71 fd ff ff 48 83 f8 ff 49 89 c6 74 74 48 89 c6 bf c0 0c 40 00 31 c0 e8 69 fd ff ff 45 85 ff 7e 21 31 c9 66 90 <41> 0f be 14 0e 01 d3 f7 c1 ff 0f 00 00 75 05 41 c6 04 0e 2a 48 83
RSP: 002b:00007ffe29ae96f0 EFLAGS: 00010206
RAX: 000000000000001b RBX: 0000000000000000 RCX: 0000000001ce1000
RDX: 0000000000000000 RSI: 000000007fffffe5 RDI: 0000000000000000
RBP: 000000000000000c R08: 0000000000000000 R09: 00007f94be09220d
R10: 0000000000000002 R11: 0000000000000246 R12: 00000000000186a0
R13: 0000000000000003 R14: 00007f949d845000 R15: 0000000002800000
Task in /leaker killed as a result of limit of /leaker
memory: usage 524288kB, limit 524288kB, failcnt 158965
memory+swap: usage 0kB, limit 9007199254740988kB, failcnt 0
kmem: usage 2016kB, limit 9007199254740988kB, failcnt 0
Memory cgroup stats for /leaker: cache:844KB rss:521136KB rss_huge:0KB shmem:0KB mapped_file:0KB dirty:132KB writeback:0KB inactive_anon:0KB active_anon:521224KB inactive_file:1012KB active_file:8KB unevictable:0KB
Memory cgroup out of memory: Kill process 2746 (leaker) score 998 or sacrifice child
Killed process 2746 (leaker) total-vm:536704kB, anon-rss:521176kB, file-rss:1208kB, shmem-rss:0kB
oom_reaper: reaped process 2746 (leaker), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB

[2]

leaker invoked oom-killer: gfp_mask=0x600040(GFP_NOFS), nodemask=(null), order=0, oom_score_adj=0
CPU: 1 PID: 2746 Comm: leaker Not tainted 4.18.0+ #20
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/13/2018
Call Trace:
dump_stack+0x63/0x88
dump_header+0x67/0x27a
? mem_cgroup_scan_tasks+0x91/0xf0
oom_kill_process+0x210/0x410
out_of_memory+0x109/0x2d0
mem_cgroup_out_of_memory+0x46/0x80
try_charge+0x58d/0x650
? __radix_tree_replace+0x81/0x100
mem_cgroup_try_charge+0x7a/0x100
__add_to_page_cache_locked+0x92/0x180
add_to_page_cache_lru+0x4d/0xf0
iomap_readpages_actor+0xde/0x1b0
? iomap_zero_range_actor+0x1d0/0x1d0
iomap_apply+0xaf/0x130
iomap_readpages+0x9f/0x150
? iomap_zero_range_actor+0x1d0/0x1d0
xfs_vm_readpages+0x18/0x20 [xfs]
read_pages+0x60/0x140
__do_page_cache_readahead+0x193/0x1b0
ondemand_readahead+0x16d/0x2c0
page_cache_async_readahead+0x9a/0xd0
filemap_fault+0x403/0x620
? alloc_set_pte+0x12c/0x540
? _cond_resched+0x14/0x30
__xfs_filemap_fault+0x66/0x180 [xfs]
xfs_filemap_fault+0x27/0x30 [xfs]
__do_fault+0x19/0x40
__handle_mm_fault+0x8e8/0xb60
handle_mm_fault+0xfd/0x220
__do_page_fault+0x238/0x4e0
do_page_fault+0x22/0x30
? page_fault+0x8/0x30
page_fault+0x1e/0x30
RIP: 0033:0x4009f0
Code: 03 00 00 00 e8 71 fd ff ff 48 83 f8 ff 49 89 c6 74 74 48 89 c6 bf c0 0c 40 00 31 c0 e8 69 fd ff ff 45 85 ff 7e 21 31 c9 66 90 <41> 0f be 14 0e 01 d3 f7 c1 ff 0f 00 00 75 05 41 c6 04 0e 2a 48 83
RSP: 002b:00007ffda45c9290 EFLAGS: 00010206
RAX: 000000000000001b RBX: 0000000000000000 RCX: 0000000001a1e000
RDX: 0000000000000000 RSI: 000000007fffffe5 RDI: 0000000000000000
RBP: 000000000000000c R08: 0000000000000000 R09: 00007f6d061ff20d
R10: 0000000000000002 R11: 0000000000000246 R12: 00000000000186a0
R13: 0000000000000003 R14: 00007f6ce59b2000 R15: 0000000002800000
Task in /leaker killed as a result of limit of /leaker
memory: usage 524288kB, limit 524288kB, failcnt 7221
memory+swap: usage 0kB, limit 9007199254740988kB, failcnt 0
kmem: usage 1944kB, limit 9007199254740988kB, failcnt 0
Memory cgroup stats for /leaker: cache:3632KB rss:518232KB rss_huge:0KB shmem:0KB mapped_file:0KB dirty:0KB writeback:0KB inactive_anon:0KB active_anon:518408KB inactive_file:3908KB active_file:12KB unevictable:0KB
Memory cgroup out of memory: Kill process 2746 (leaker) score 992 or sacrifice child
Killed process 2746 (leaker) total-vm:536704kB, anon-rss:518264kB, file-rss:1188kB, shmem-rss:0kB
oom_reaper: reaped process 2746 (leaker), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB

[3]

leaker invoked oom-killer: gfp_mask=0x50, order=0, oom_score_adj=0
leaker cpuset=/ mems_allowed=0
CPU: 1 PID: 3206 Comm: leaker Not tainted 3.10.0-957.27.2.el7.x86_64 #1
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/13/2018
Call Trace:
[<ffffffffaf364147>] dump_stack+0x19/0x1b
[<ffffffffaf35eb6a>] dump_header+0x90/0x229
[<ffffffffaedbb456>] ? find_lock_task_mm+0x56/0xc0
[<ffffffffaee32a38>] ? try_get_mem_cgroup_from_mm+0x28/0x60
[<ffffffffaedbb904>] oom_kill_process+0x254/0x3d0
[<ffffffffaee36c36>] mem_cgroup_oom_synchronize+0x546/0x570
[<ffffffffaee360b0>] ? mem_cgroup_charge_common+0xc0/0xc0
[<ffffffffaedbc194>] pagefault_out_of_memory+0x14/0x90
[<ffffffffaf35d072>] mm_fault_error+0x6a/0x157
[<ffffffffaf3717c8>] __do_page_fault+0x3c8/0x4f0
[<ffffffffaf371925>] do_page_fault+0x35/0x90
[<ffffffffaf36d768>] page_fault+0x28/0x30
Task in /leaker killed as a result of limit of /leaker
memory: usage 524288kB, limit 524288kB, failcnt 20628
memory+swap: usage 524288kB, limit 9007199254740988kB, failcnt 0
kmem: usage 0kB, limit 9007199254740988kB, failcnt 0
Memory cgroup stats for /leaker: cache:840KB rss:523448KB rss_huge:0KB mapped_file:0KB swap:0KB inactive_anon:0KB active_anon:523448KB inactive_file:464KB active_file:376KB unevictable:0KB
Memory cgroup out of memory: Kill process 3206 (leaker) score 970 or sacrifice child
Killed process 3206 (leaker) total-vm:536692kB, anon-rss:523304kB, file-rss:412kB, shmem-rss:0kB

---
mm/oom_kill.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index eda2e2a..26804ab 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -1068,9 +1068,10 @@ bool out_of_memory(struct oom_control *oc)
* The OOM killer does not compensate for IO-less reclaim.
* pagefault_out_of_memory lost its gfp context so we have to
* make sure exclude 0 mask - all other users should have at least
- * ___GFP_DIRECT_RECLAIM to get here.
+ * ___GFP_DIRECT_RECLAIM to get here. But mem_cgroup_oom() has to
+ * invoke the OOM killer even if it is a GFP_NOFS allocation.
*/
- if (oc->gfp_mask && !(oc->gfp_mask & __GFP_FS))
+ if (oc->gfp_mask && !(oc->gfp_mask & __GFP_FS) && !is_memcg_oom(oc))
return true;

/*
--
1.8.3.1

Next message: Vignesh Raghavendra: "Re: [PATCH 6/7] mtd: spi-nor: Rework the SPI NOR lock/unlock logic"
Previous message: Manivannan Sadhasivam: "Re: [PATCH v2 1/1] arm64: dts: rockchip: Add support for TB-96AI board"
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