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authorHugh Dickins <hughd@google.com>2022-04-01 11:28:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-04-01 11:46:09 -0700
commitece369c7e1044a333dc002d3c3c228b8853fc5f7 (patch)
treebe4173a6317ad6455505361deca0d325bdd34470 /mm/gup.c
parentcdd81b313d5e09e8a248c2dbd9c6b069f82e5d71 (diff)
mm/munlock: add lru_add_drain() to fix memcg_stat_test
Mike reports that LTP memcg_stat_test usually leads to memcg_stat_test 3 TINFO: Test unevictable with MAP_LOCKED memcg_stat_test 3 TINFO: Running memcg_process --mmap-lock1 -s 135168 memcg_stat_test 3 TINFO: Warming up pid: 3460 memcg_stat_test 3 TINFO: Process is still here after warm up: 3460 memcg_stat_test 3 TFAIL: unevictable is 122880, 135168 expected but may also lead to memcg_stat_test 4 TINFO: Test unevictable with mlock memcg_stat_test 4 TINFO: Running memcg_process --mmap-lock2 -s 135168 memcg_stat_test 4 TINFO: Warming up pid: 4271 memcg_stat_test 4 TINFO: Process is still here after warm up: 4271 memcg_stat_test 4 TFAIL: unevictable is 122880, 135168 expected or both. A wee bit flaky. follow_page_pte() used to have an lru_add_drain() per each page mlocked, and the test came to rely on accurate stats. The pagevec to be drained is different now, but still covered by lru_add_drain(); and, never mind the test, I believe it's in everyone's interest that a bulk faulting interface like populate_vma_page_range() or faultin_vma_page_range() should drain its local pagevecs at the end, to save others sometimes needing the much more expensive lru_add_drain_all(). This does not absolutely guarantee exact stats - the mlocking task can be migrated between CPUs as it proceeds - but it's good enough and the tests pass. Link: https://lkml.kernel.org/r/47f6d39c-a075-50cb-1cfb-26dd957a48af@google.com Fixes: b67bf49ce7aa ("mm/munlock: delete FOLL_MLOCK and FOLL_POPULATE") Signed-off-by: Hugh Dickins <hughd@google.com> Reported-by: Mike Galbraith <efault@gmx.de> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
-rw-r--r--mm/gup.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 271fbe8195d7..f598a037eb04 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1404,6 +1404,7 @@ long populate_vma_page_range(struct vm_area_struct *vma,
struct mm_struct *mm = vma->vm_mm;
unsigned long nr_pages = (end - start) / PAGE_SIZE;
int gup_flags;
+ long ret;
VM_BUG_ON(!PAGE_ALIGNED(start));
VM_BUG_ON(!PAGE_ALIGNED(end));
@@ -1438,8 +1439,10 @@ long populate_vma_page_range(struct vm_area_struct *vma,
* We made sure addr is within a VMA, so the following will
* not result in a stack expansion that recurses back here.
*/
- return __get_user_pages(mm, start, nr_pages, gup_flags,
+ ret = __get_user_pages(mm, start, nr_pages, gup_flags,
NULL, NULL, locked);
+ lru_add_drain();
+ return ret;
}
/*
@@ -1471,6 +1474,7 @@ long faultin_vma_page_range(struct vm_area_struct *vma, unsigned long start,
struct mm_struct *mm = vma->vm_mm;
unsigned long nr_pages = (end - start) / PAGE_SIZE;
int gup_flags;
+ long ret;
VM_BUG_ON(!PAGE_ALIGNED(start));
VM_BUG_ON(!PAGE_ALIGNED(end));
@@ -1498,8 +1502,10 @@ long faultin_vma_page_range(struct vm_area_struct *vma, unsigned long start,
if (check_vma_flags(vma, gup_flags))
return -EINVAL;
- return __get_user_pages(mm, start, nr_pages, gup_flags,
+ ret = __get_user_pages(mm, start, nr_pages, gup_flags,
NULL, NULL, locked);
+ lru_add_drain();
+ return ret;
}
/*