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Thu, 26 May 2022 19:15:37 -0400 (EDT) From: Zi Yan To: Andrew Morton , David Hildenbrand , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Qian Cai , Vlastimil Babka , Mel Gorman , Eric Ren , Mike Rapoport , Oscar Salvador , Christophe Leroy , Zi Yan , Marek Szyprowski , Michael Walle Subject: [PATCH 1/2] mm: page-isolation: skip isolated pageblock in start_isolate_page_range() Date: Thu, 26 May 2022 19:15:30 -0400 Message-Id: <20220526231531.2404977-1-zi.yan@sent.com> X-Mailer: git-send-email 2.35.1 Reply-To: Zi Yan MIME-Version: 1.0 X-Rspamd-Queue-Id: 4700F180055 X-Stat-Signature: p413gggeex6p63s3n4j1uyi7ruemg8g1 Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=sent.com header.s=fm1 header.b=r+k3sseN; dkim=pass header.d=messagingengine.com header.s=fm1 header.b=vTaJwHRx; dmarc=pass (policy=none) header.from=sent.com; spf=pass (imf16.hostedemail.com: domain of zi.yan@sent.com designates 66.111.4.26 as permitted sender) smtp.mailfrom=zi.yan@sent.com X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1653606925-357605 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Zi Yan 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(). Fixes: 88ee134320b8 ("mm: fix a potential infinite loop in start_isolate_page_range()") 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/ Signed-off-by: Zi Yan --- 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;