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Subject[PATCH 4.9 214/329] mm, thp: do not cause memcg oom for thp
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Rientjes <rientjes@google.com>

[ Upstream commit 9d3c3354bb85bab4d865fe95039443f09a4c8394 ]

Commit 2516035499b9 ("mm, thp: remove __GFP_NORETRY from khugepaged and
madvised allocations") changed the page allocator to no longer detect
thp allocations based on __GFP_NORETRY.

It did not, however, modify the mem cgroup try_charge() path to avoid
oom kill for either khugepaged collapsing or thp faulting. It is never
expected to oom kill a process to allocate a hugepage for thp; reclaim
is governed by the thp defrag mode and MADV_HUGEPAGE, but allocations
(and charging) should fallback instead of oom killing processes.

Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1803191409420.124411@chino.kir.corp.google.com
Fixes: 2516035499b9 ("mm, thp: remove __GFP_NORETRY from khugepaged and madvised allocations")
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/huge_memory.c | 5 +++--
mm/khugepaged.c | 8 ++++++--
2 files changed, 9 insertions(+), 4 deletions(-)

--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -542,7 +542,8 @@ static int __do_huge_pmd_anonymous_page(

VM_BUG_ON_PAGE(!PageCompound(page), page);

- if (mem_cgroup_try_charge(page, vma->vm_mm, gfp, &memcg, true)) {
+ if (mem_cgroup_try_charge(page, vma->vm_mm, gfp | __GFP_NORETRY, &memcg,
+ true)) {
put_page(page);
count_vm_event(THP_FAULT_FALLBACK);
return VM_FAULT_FALLBACK;
@@ -1060,7 +1061,7 @@ alloc:
}

if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
- huge_gfp, &memcg, true))) {
+ huge_gfp | __GFP_NORETRY, &memcg, true))) {
put_page(new_page);
split_huge_pmd(vma, fe->pmd, fe->address);
if (page)
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -963,7 +963,9 @@ static void collapse_huge_page(struct mm
goto out_nolock;
}

- if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) {
+ /* Do not oom kill for khugepaged charges */
+ if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp | __GFP_NORETRY,
+ &memcg, true))) {
result = SCAN_CGROUP_CHARGE_FAIL;
goto out_nolock;
}
@@ -1323,7 +1325,9 @@ static void collapse_shmem(struct mm_str
goto out;
}

- if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) {
+ /* Do not oom kill for khugepaged charges */
+ if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp | __GFP_NORETRY,
+ &memcg, true))) {
result = SCAN_CGROUP_CHARGE_FAIL;
goto out;
}

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