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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2015-04-15 16:14:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-15 16:35:19 -0700
commitbcc54222309c70ebcb6c69c156fba4a13dee0a3b (patch)
tree2d947c66bdc0391d5294dd5fdd87cbabfa032020 /mm/memory-failure.c
parent822fc61367f062d36c5b5a4d517e9bd2b65a741f (diff)
downloadlwn-bcc54222309c70ebcb6c69c156fba4a13dee0a3b.tar.gz
lwn-bcc54222309c70ebcb6c69c156fba4a13dee0a3b.zip
mm: hugetlb: introduce page_huge_active
We are not safe from calling isolate_huge_page() on a hugepage concurrently, which can make the victim hugepage in invalid state and results in BUG_ON(). The root problem of this is that we don't have any information on struct page (so easily accessible) about hugepages' activeness. Note that hugepages' activeness means just being linked to hstate->hugepage_activelist, which is not the same as normal pages' activeness represented by PageActive flag. Normal pages are isolated by isolate_lru_page() which prechecks PageLRU before isolation, so let's do similarly for hugetlb with a new paeg_huge_active(). set/clear_page_huge_active() should be called within hugetlb_lock. But hugetlb_cow() and hugetlb_no_page() don't do this, being justified because in these functions set_page_huge_active() is called right after the hugepage is allocated and no other thread tries to isolate it. [akpm@linux-foundation.org: s/PageHugeActive/page_huge_active/, make it return bool] [fengguang.wu@intel.com: set_page_huge_active() can be static] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory-failure.c')
-rw-r--r--mm/memory-failure.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5fd8931d8c31..d9359b770cd9 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1586,8 +1586,18 @@ static int soft_offline_huge_page(struct page *page, int flags)
}
unlock_page(hpage);
- /* Keep page count to indicate a given hugepage is isolated. */
- list_move(&hpage->lru, &pagelist);
+ ret = isolate_huge_page(hpage, &pagelist);
+ if (ret) {
+ /*
+ * get_any_page() and isolate_huge_page() takes a refcount each,
+ * so need to drop one here.
+ */
+ put_page(hpage);
+ } else {
+ pr_info("soft offline: %#lx hugepage failed to isolate\n", pfn);
+ return -EBUSY;
+ }
+
ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
MIGRATE_SYNC, MR_MEMORY_FAILURE);
if (ret) {