memcg, thp: do not invoke oom killer on thp charges

A THP memcg charge can trigger the oom killer since 2516035499b9 ("mm,
thp: remove __GFP_NORETRY from khugepaged and madvised allocations").
We have used an explicit __GFP_NORETRY previously which ruled the OOM
killer automagically.

Memcg charge path should be semantically compliant with the allocation
path and that means that if we do not trigger the OOM killer for costly
orders which should do the same in the memcg charge path as well.
Otherwise we are forcing callers to distinguish the two and use
different gfp masks which is both non-intuitive and bug prone.  As soon
as we get a costly high order kmalloc user we even do not have any means
to tell the memcg specific gfp mask to prevent from OOM because the
charging is deep within guts of the slab allocator.

The unexpected memcg OOM on THP has already been fixed upstream by
9d3c3354bb85 ("mm, thp: do not cause memcg oom for thp") but this is a
one-off fix rather than a generic solution.  Teach mem_cgroup_oom to
bail out on costly order requests to fix the THP issue as well as any
other costly OOM eligible allocations to be added in future.

Also revert 9d3c3354bb85 because special gfp for THP is no longer
needed.

Link: http://lkml.kernel.org/r/20180403193129.22146-1-mhocko@kernel.org
Fixes: 2516035499b9 ("mm, thp: remove __GFP_NORETRY from khugepaged and madvised allocations")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f0ae8d1d4329d5c72c9bcf9e460e16a7815a1059..229ab8c75a6b01b9e92c31751e4c1923b98cf1fc 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -555,8 +555,7 @@ 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 | __GFP_NORETRY, &memcg,
-                                 true)) {
+       if (mem_cgroup_try_charge(page, vma->vm_mm, gfp, &memcg, true)) {
                put_page(page);
                count_vm_event(THP_FAULT_FALLBACK);
                return VM_FAULT_FALLBACK;
@@ -1317,7 +1316,7 @@ alloc:
        }
 
        if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
-                               huge_gfp | __GFP_NORETRY, &memcg, true))) {
+                                       huge_gfp, &memcg, true))) {
                put_page(new_page);
                split_huge_pmd(vma, vmf->pmd, vmf->address);
                if (page)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index e42568284e06038ab70ec1344f63a2e5182ea90d..c15da1ea7e639bc0ab56bc747a4f7110c38f7187 100644 (file)
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -965,9 +965,7 @@ static void collapse_huge_page(struct mm_struct *mm,
                goto out_nolock;
        }
 
-       /* Do not oom kill for khugepaged charges */
-       if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp | __GFP_NORETRY,
-                                          &memcg, true))) {
+       if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) {
                result = SCAN_CGROUP_CHARGE_FAIL;
                goto out_nolock;
        }
@@ -1326,9 +1324,7 @@ static void collapse_shmem(struct mm_struct *mm,
                goto out;
        }
 
-       /* Do not oom kill for khugepaged charges */
-       if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp | __GFP_NORETRY,
-                                          &memcg, true))) {
+       if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) {
                result = SCAN_CGROUP_CHARGE_FAIL;
                goto out;
        }

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9ec024b862aca01cb32d302584e6b110d11107a7..6b4f5c0a8eefdf49539532517d08c19e0dfef276 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1485,7 +1485,7 @@ static void memcg_oom_recover(struct mem_cgroup *memcg)
 
 static void mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
 {
-       if (!current->memcg_may_oom)
+       if (!current->memcg_may_oom || order > PAGE_ALLOC_COSTLY_ORDER)
                return;
        /*
         * We are in the middle of the charge context here, so we