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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id 126sm974999oii.39.2020.06.11.15.28.54 (version=TLS1 cipher=ECDHE-ECDSA-AES128-SHA bits=128/128); Thu, 11 Jun 2020 15:28:56 -0700 (PDT) Date: Thu, 11 Jun 2020 15:28:54 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Alex Shi cc: akpm@linux-foundation.org, mgorman@techsingularity.net, tj@kernel.org, khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com, yang.shi@linux.alibaba.com, willy@infradead.org, hannes@cmpxchg.org, lkp@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, shakeelb@google.com, iamjoonsoo.kim@lge.com, richard.weiyang@gmail.com Subject: [PATCH alexv12 1/2] mm/compaction: fix isolate_migratepages_block() fails Message-ID: User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Fix lots of crashes under compaction load: isolate_migratepages_block() must clean up appropriately when rejecting a page, setting PageLRU again if it had been cleared; and a put_page() after get_page_unless_zero() cannot safely be done while holding locked_lruvec - it may turn out to be the final put_page(), which will take an lruvec lock when PageLRU. Signed-off-by: Hugh Dickins --- These fixes should be folded into 10/16 and 12/16, I have not tried to figure out what belongs in which. mm/compaction.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) --- alexv12/mm/compaction.c 2020-06-11 13:24:52.037154793 -0700 +++ hughd/mm/compaction.c 2020-06-11 13:48:10.437046025 -0700 @@ -879,6 +879,7 @@ isolate_migratepages_block(struct compac if (!valid_page && IS_ALIGNED(low_pfn, pageblock_nr_pages)) { if (!cc->ignore_skip_hint && get_pageblock_skip(page)) { low_pfn = end_pfn; + page = NULL; goto isolate_abort; } valid_page = page; @@ -971,10 +972,8 @@ isolate_migratepages_block(struct compac goto isolate_fail; /* Try isolate the page */ - if (!TestClearPageLRU(page)) { - put_page(page); - goto isolate_fail; - } + if (!TestClearPageLRU(page)) + goto isolate_fail_put; rcu_read_lock(); lruvec = mem_cgroup_page_lruvec(page, pgdat); @@ -1005,7 +1004,8 @@ isolate_migratepages_block(struct compac */ if (unlikely(PageCompound(page) && !cc->alloc_contig)) { low_pfn += compound_nr(page) - 1; - goto isolate_fail; + SetPageLRU(page); + goto isolate_fail_put; } } else rcu_read_unlock(); @@ -1038,6 +1038,15 @@ isolate_success: } continue; + +isolate_fail_put: + /* Avoid potential deadlock in freeing page under lru_lock */ + if (locked_lruvec) { + unlock_page_lruvec_irqrestore(locked_lruvec, flags); + locked_lruvec = NULL; + } + put_page(page); + isolate_fail: if (!skip_on_failure) continue; @@ -1074,10 +1083,15 @@ isolate_fail: */ if (unlikely(low_pfn > end_pfn)) low_pfn = end_pfn; + page = NULL; isolate_abort: if (locked_lruvec) unlock_page_lruvec_irqrestore(locked_lruvec, flags); + if (page) { + SetPageLRU(page); + put_page(page); + } /* * Updated the cached scanner pfn once the pageblock has been scanned