From nobody Thu Dec 18 02:26:13 2025 Received: from out30-112.freemail.mail.aliyun.com (out30-112.freemail.mail.aliyun.com [115.124.30.112]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1D800D502 for ; Sat, 15 Jun 2024 03:50:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.112 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718423417; cv=none; b=FXFcS1Nbaycc2b3XuVk8nkUpzNz/LaW9UO2GJX1o3d9JFtEqZu4ylZ8VvolPZiIiMT+Y9RJTyvhCh95xj5yIWitMnxTOTnYvRkPc+28SCOxBWQYO84yExx2ZhisfpqUB1VL93w6pRSnJryWpF9bVK9mOOLtKpJ1P73nrlPU0hJo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718423417; c=relaxed/simple; bh=jtzSl7eCWM99+KaJ9+9rcukc22zH4iB/trYcC6ShkaQ=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=ozTeSiIuuuby6gBS1soWxjVQURVY8xs0VqOdSVdP6wDvOg1q5M40HUKHOrpdmHt5LEAj8XJlqki5dtShiiz8SQMJm4WnHAcN5cGyS1FFg2wWGwvoGex7lrUYcfSLNTUA3QIwPJhDg8dbAPH4QxZEO5NNtOGH3aKMqzq6BdUm/Dc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=I/K+Qbk9; arc=none smtp.client-ip=115.124.30.112 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="I/K+Qbk9" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1718423407; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=qyDcsqG1G9+ch9xsh4NPmqEryYrFj8x1o1BGt5MbPo0=; b=I/K+Qbk9vTHuyzQ+AQAqMuKQmnAzFqx985JuDFu+lS/fkqGmoWgnAXLP6XgL4kJHZ8m0EtVUxhk6YwZ3CR830/58cIoRjFQIrrMufAU1mMLFl/KjouL1NHFT24SwoC0tA9dts7TXV1ym0lrkiVPHcDxrModhPXOlC5s0UaNek7g= X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R131e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033045075189;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=13;SR=0;TI=SMTPD_---0W8SZ6-6_1718423405; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0W8SZ6-6_1718423405) by smtp.aliyun-inc.com; Sat, 15 Jun 2024 11:50:06 +0800 From: Baolin Wang To: akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, hannes@cmpxchg.org, nphamcs@gmail.com, yosryahmed@google.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v3] mm: shmem: fix getting incorrect lruvec when replacing a shmem folio Date: Sat, 15 Jun 2024 11:49:54 +0800 Message-Id: X-Mailer: git-send-email 2.39.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When testing shmem swapin, I encountered the warning below on my machine. The reason is that replacing an old shmem folio with a new one causes mem_cgroup_migrate() to clear the old folio's memcg data. As a result, the old folio cannot get the correct memcg's lruvec needed to remove itself from the LRU list when it is being freed. This could lead to possible serio= us problems, such as LRU list crashes due to holding the wrong LRU lock, and incorrect LRU statistics. To fix this issue, we can fallback to use the mem_cgroup_replace_folio() to replace the old shmem folio. [ 5241.100311] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0= x0 pfn:0x5d9960 [ 5241.100317] head: order:4 mapcount:0 entire_mapcount:0 nr_pages_mapped:0= pincount:0 [ 5241.100319] flags: 0x17fffe0000040068(uptodate|lru|head|swapbacked|node= =3D0|zone=3D2|lastcpupid=3D0x3ffff) [ 5241.100323] raw: 17fffe0000040068 fffffdffd6687948 fffffdffd69ae008 0000= 000000000000 [ 5241.100325] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000= 000000000000 [ 5241.100326] head: 17fffe0000040068 fffffdffd6687948 fffffdffd69ae008 000= 0000000000000 [ 5241.100327] head: 0000000000000000 0000000000000000 00000000ffffffff 000= 0000000000000 [ 5241.100328] head: 17fffe0000000204 fffffdffd6665801 ffffffffffffffff 000= 0000000000000 [ 5241.100329] head: 0000000a00000010 0000000000000000 00000000ffffffff 000= 0000000000000 [ 5241.100330] page dumped because: VM_WARN_ON_ONCE_FOLIO(!memcg && !mem_cg= roup_disabled()) [ 5241.100338] ------------[ cut here ]------------ [ 5241.100339] WARNING: CPU: 19 PID: 78402 at include/linux/memcontrol.h:77= 5 folio_lruvec_lock_irqsave+0x140/0x150 [...] [ 5241.100374] pc : folio_lruvec_lock_irqsave+0x140/0x150 [ 5241.100375] lr : folio_lruvec_lock_irqsave+0x138/0x150 [ 5241.100376] sp : ffff80008b38b930 [...] [ 5241.100398] Call trace: [ 5241.100399] folio_lruvec_lock_irqsave+0x140/0x150 [ 5241.100401] __page_cache_release+0x90/0x300 [ 5241.100404] __folio_put+0x50/0x108 [ 5241.100406] shmem_replace_folio+0x1b4/0x240 [ 5241.100409] shmem_swapin_folio+0x314/0x528 [ 5241.100411] shmem_get_folio_gfp+0x3b4/0x930 [ 5241.100412] shmem_fault+0x74/0x160 [ 5241.100414] __do_fault+0x40/0x218 [ 5241.100417] do_shared_fault+0x34/0x1b0 [ 5241.100419] do_fault+0x40/0x168 [ 5241.100420] handle_pte_fault+0x80/0x228 [ 5241.100422] __handle_mm_fault+0x1c4/0x440 [ 5241.100424] handle_mm_fault+0x60/0x1f0 [ 5241.100426] do_page_fault+0x120/0x488 [ 5241.100429] do_translation_fault+0x4c/0x68 [ 5241.100431] do_mem_abort+0x48/0xa0 [ 5241.100434] el0_da+0x38/0xc0 [ 5241.100436] el0t_64_sync_handler+0x68/0xc0 [ 5241.100437] el0t_64_sync+0x14c/0x150 [ 5241.100439] ---[ end trace 0000000000000000 ]--- Fixes: 85ce2c517ade ("memcontrol: only transfer the memcg data for migratio= n") Signed-off-by: Baolin Wang Reviewed-by: Shakeel Butt --- Changes from v2: - Remove the less helpful comments, per Matthew. Changes from v1: - Add reviewed tag from Shakeel. - Update related comments, per Yosry. --- mm/memcontrol.c | 3 +-- mm/shmem.c | 2 +- 2 files changed, 2 insertions(+), 3 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a811dfff10cd..c976db6a34c0 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -7780,8 +7780,7 @@ void __mem_cgroup_uncharge_folios(struct folio_batch = *folios) * @new: Replacement folio. * * Charge @new as a replacement folio for @old. @old will - * be uncharged upon free. This is only used by the page cache - * (in replace_page_cache_folio()). + * be uncharged upon free. * * Both folios must be locked, @new->mapping must be set up. */ diff --git a/mm/shmem.c b/mm/shmem.c index 99bd3c34f0fb..4acaf02bfe44 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1908,7 +1908,7 @@ static int shmem_replace_folio(struct folio **foliop,= gfp_t gfp, xa_lock_irq(&swap_mapping->i_pages); error =3D shmem_replace_entry(swap_mapping, swap_index, old, new); if (!error) { - mem_cgroup_migrate(old, new); + mem_cgroup_replace_folio(old, new); __lruvec_stat_mod_folio(new, NR_FILE_PAGES, 1); __lruvec_stat_mod_folio(new, NR_SHMEM, 1); __lruvec_stat_mod_folio(old, NR_FILE_PAGES, -1); --=20 2.39.3