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    Subject[PATCH 4.14 289/496] mm, thp: do not cause memcg oom for thp
    Date
    4.14-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
    @@ -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;
    }

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