From 9b209e557d698f24317d2619d8628b98b6728e4f Mon Sep 17 00:00:00 2001 From: Zi Yan Date: Thu, 26 May 2022 19:15:30 -0400 Subject: [PATCH] mm: page-isolation: skip isolated pageblock in start_isolate_page_range() start_isolate_page_range() first isolates the first and the last pageblocks in the range and ensure pages across range boundaries are split during isolation. But it missed the case when the range is <= a pageblock and the first and the last pageblocks are the same one, so the second isolate_single_pageblock() will always fail. To fix it, skip the pageblock isolation in second isolate_single_pageblock(). Link: https://lkml.kernel.org/r/20220526231531.2404977-1-zi.yan@sent.com Fixes: 88ee134320b8 ("mm: fix a potential infinite loop in start_isolate_page_range()") Signed-off-by: Zi Yan Reported-by: Marek Szyprowski Tested-by: Marek Szyprowski Link: https://lore.kernel.org/linux-mm/ac65adc0-a7e4-cdfe-a0d8-757195b86293@samsung.com/ Reported-by: Michael Walle Tested-by: Michael Walle Link: https://lore.kernel.org/linux-mm/8ca048ca8b547e0dd1c95387ee05c23d@walle.cc/ Cc: Christophe Leroy Cc: David Hildenbrand Cc: Doug Berger Cc: Eric Ren Cc: Mel Gorman Cc: Mike Rapoport Cc: Oscar Salvador Cc: Qian Cai Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/page_isolation.c | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-) diff --git a/mm/page_isolation.c b/mm/page_isolation.c index c643c8420809..fbd820b21292 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -300,7 +300,7 @@ __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) + gfp_t gfp_flags, bool isolate_before, bool skip_isolation) { unsigned char saved_mt; unsigned long start_pfn; @@ -327,11 +327,16 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags, zone->zone_start_pfn); saved_mt = get_pageblock_migratetype(pfn_to_page(isolate_pageblock)); - ret = set_migratetype_isolate(pfn_to_page(isolate_pageblock), saved_mt, flags, - isolate_pageblock, isolate_pageblock + pageblock_nr_pages); - if (ret) - return ret; + 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); + + if (ret) + return ret; + } /* * Bail out early when the to-be-isolated pageblock does not form @@ -463,7 +468,8 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags, return 0; failed: /* restore the original migratetype */ - unset_migratetype_isolate(pfn_to_page(isolate_pageblock), saved_mt); + if (!skip_isolation) + unset_migratetype_isolate(pfn_to_page(isolate_pageblock), saved_mt); return -EBUSY; } @@ -522,14 +528,18 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, unsigned long isolate_start = ALIGN_DOWN(start_pfn, pageblock_nr_pages); unsigned long isolate_end = ALIGN(end_pfn, pageblock_nr_pages); int ret; + bool skip_isolation = false; /* isolate [isolate_start, isolate_start + pageblock_nr_pages) pageblock */ - ret = isolate_single_pageblock(isolate_start, flags, gfp_flags, false); + ret = isolate_single_pageblock(isolate_start, flags, gfp_flags, false, skip_isolation); if (ret) return ret; + if (isolate_start == isolate_end - pageblock_nr_pages) + skip_isolation = true; + /* isolate [isolate_end - pageblock_nr_pages, isolate_end) pageblock */ - ret = isolate_single_pageblock(isolate_end, flags, gfp_flags, true); + ret = isolate_single_pageblock(isolate_end, flags, gfp_flags, true, skip_isolation); if (ret) { unset_migratetype_isolate(pfn_to_page(isolate_start), migratetype); return ret; -- 2.11.0