From: Zi Yan ziy@nvidia.com

set_migratetype_isolate() does not allow isolating MIGRATE_CMA pageblocks unless it is used for CMA allocation. isolate_single_pageblock() did not have the same behavior when it is used together with set_migratetype_isolate() in start_isolate_page_range(). This allows alloc_contig_range() with migratetype other than MIGRATE_CMA, like MIGRATE_MOVABLE (used by alloc_contig_pages()), to isolate first and last pageblock but fail the rest. The failure leads to changing migratetype of the first and last pageblock to MIGRATE_MOVABLE from MIGRATE_CMA, corrupting the CMA region. This can happen during gigantic page allocations.

Fix it by passing migratetype into isolate_single_pageblock(), so that set_migratetype_isolate() used by isolate_single_pageblock() will prevent the isolation happening.

Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity") Reported-by: Doug Berger opendmb@gmail.com Signed-off-by: Zi Yan ziy@nvidia.com Cc: stable@vger.kernel.org --- mm/page_isolation.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c index c66d61e0bc72..04141a9bea70 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -288,6 +288,7 @@ __first_valid_page(unsigned long pfn, unsigned long nr_pages) * @isolate_before: isolate the pageblock before the boundary_pfn * @skip_isolation: the flag to skip the pageblock isolation in second * isolate_single_pageblock() + * @migratetype: migrate type to set in error recovery. * * Free and in-use pages can be as big as MAX_ORDER-1 and contain more than one * pageblock. When not all pageblocks within a page are isolated at the same @@ -302,9 +303,9 @@ __first_valid_page(unsigned long pfn, unsigned long nr_pages) * the in-use page then splitting the free page. */ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags, - gfp_t gfp_flags, bool isolate_before, bool skip_isolation) + gfp_t gfp_flags, bool isolate_before, bool skip_isolation, + int migratetype) { - unsigned char saved_mt; unsigned long start_pfn; unsigned long isolate_pageblock; unsigned long pfn; @@ -328,13 +329,13 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags, start_pfn = max(ALIGN_DOWN(isolate_pageblock, MAX_ORDER_NR_PAGES), zone->zone_start_pfn);

- saved_mt = get_pageblock_migratetype(pfn_to_page(isolate_pageblock)); + if (skip_isolation) { + int mt = get_pageblock_migratetype(pfn_to_page(isolate_pageblock));

- if (skip_isolation) - VM_BUG_ON(!is_migrate_isolate(saved_mt)); - else { - ret = set_migratetype_isolate(pfn_to_page(isolate_pageblock), saved_mt, flags, - isolate_pageblock, isolate_pageblock + pageblock_nr_pages); + VM_BUG_ON(!is_migrate_isolate(mt)); + } else { + ret = set_migratetype_isolate(pfn_to_page(isolate_pageblock), migratetype, + flags, isolate_pageblock, isolate_pageblock + pageblock_nr_pages);

if (ret) return ret; @@ -475,7 +476,7 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags, failed: /* restore the original migratetype */ if (!skip_isolation) - unset_migratetype_isolate(pfn_to_page(isolate_pageblock), saved_mt); + unset_migratetype_isolate(pfn_to_page(isolate_pageblock), migratetype); return -EBUSY; }

@@ -537,7 +538,8 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, bool skip_isolation = false;

/* isolate [isolate_start, isolate_start + pageblock_nr_pages) pageblock */ - ret = isolate_single_pageblock(isolate_start, flags, gfp_flags, false, skip_isolation); + ret = isolate_single_pageblock(isolate_start, flags, gfp_flags, false, + skip_isolation, migratetype); if (ret) return ret;

@@ -545,7 +547,8 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, skip_isolation = true;

/* isolate [isolate_end - pageblock_nr_pages, isolate_end) pageblock */ - ret = isolate_single_pageblock(isolate_end, flags, gfp_flags, true, skip_isolation); + ret = isolate_single_pageblock(isolate_end, flags, gfp_flags, true, + skip_isolation, migratetype); if (ret) { unset_migratetype_isolate(pfn_to_page(isolate_start), migratetype); return ret;