mm, migration: do not trigger OOM killer when migrating memory

Page migration (for memory hotplug, soft_offline_page or mbind) needs to
allocate a new memory.  This can trigger an oom killer if the target
memory is depleated.  Although quite unlikely, still possible,
especially for the memory hotplug (offlining of memoery).

Up to now we didn't really have reasonable means to back off.
__GFP_NORETRY can fail just too easily and __GFP_THISNODE sticks to a
single node and that is not suitable for all callers.

But now that we have __GFP_RETRY_MAYFAIL we should use it.  It is
preferable to fail the migration than disrupt the system by killing some
processes.

Link: http://lkml.kernel.org/r/20170623085345.11304-7-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alex Belits <alex.belits@cavium.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: NeilBrown <neilb@suse.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 4634da521238f18d76155d8e92870f587f6da163..3e0d405dc842d5dd65b28cb710b4ce38008ca64b 100644 (file)
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -34,7 +34,7 @@ extern char *migrate_reason_names[MR_TYPES];
 static inline struct page *new_page_nodemask(struct page *page,
                                int preferred_nid, nodemask_t *nodemask)
 {
-       gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
+       gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL;
 
        if (PageHuge(page))
                return alloc_huge_page_nodemask(page_hstate(compound_head(page)),

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 7d8e56214ac099ad7c0a1eb8201d344a008428f1..d911fa5cb2a73fe464042a59e1c2676c1129239d 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1078,7 +1078,8 @@ static struct page *new_page(struct page *page, unsigned long start, int **x)
        /*
         * if !vma, alloc_page_vma() will use task or system default policy
         */
-       return alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
+       return alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_RETRY_MAYFAIL,
+                       vma, address);
 }
 #else