[PATCH 4.14 289/496] mm, thp: do not cause memcg oom for thp

From: Greg Kroah-Hartman
Date: Mon May 28 2018 - 08:57:42 EST


4.14-stable review patch. If anyone has any objections, please let me know.

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

From: David Rientjes <rientjes@xxxxxxxxxx>

[ 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@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 2516035499b9 ("mm, thp: remove __GFP_NORETRY from khugepaged and madvised allocations")
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -555,7 +555,8 @@ 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;
@@ -1304,7 +1305,7 @@ 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, vmf->pmd, vmf->address);
if (page)
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -965,7 +965,9 @@ 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;
}
@@ -1324,7 +1326,9 @@ 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;
}