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Commit 9d3c3354 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mm, thp: do not cause memcg oom for thp 

Commit 25160354 ("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: 25160354 ("mm, thp: remove __GFP_NORETRY from khugepaged and madvised allocations")
Signed-off-by: default avatarDavid 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1c610d5f

mm/huge_memory.c

+3 −2
Original line number Diff line number Diff line
@@ -555,7 +555,8 @@ static int __do_huge_pmd_anonymous_page(struct vm_fault *vmf, struct page *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;
@@ -1316,7 +1317,7 @@ int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) 
	}



	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)

mm/khugepaged.c

+6 −2
Original line number Diff line number Diff line
@@ -965,7 +965,9 @@ static void collapse_huge_page(struct mm_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_struct *mm, 
		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;

	}