From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-111.freemail.mail.aliyun.com (out30-111.freemail.mail.aliyun.com [115.124.30.111]) (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 CD3F236C for ; Fri, 14 Jun 2024 00:45:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.111 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718325931; cv=none; b=DWZPrQpZnXLNjZlfuZzmk0VUMA8bINttu2pl6qcuVBUs672i1D0FfShX+QPwmEwK4vYqF3IvIn7hEiUMV5mCEH9ZTFkyHI3pNZmHuwMARhUJKxrnOLUR6ExVuG0suBCBjq37GQArYuW33GJVWpa0p6fGFBCt52xI9SgHfeU1yoY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718325931; c=relaxed/simple; bh=+jMS/xbYOImcqZhfvBmN0HrXors2OJkh7ZVEIcwy8Yc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=nYzU99bLcl3uuC88wqQ7CoXvlPVFtCZNPwy4eJWWZR1tkE4+6r0NAWNa3pLkeYO7qj7188Io2OEBDN87iMtzqxDndcQTv+VIr3v73vn/BbrUUBeLIx3gM9seKbcRQ6B37/04w604Czt0iyadypvGdC++u3S6vZSRJvswzzl/SYA= 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=eGWo8Zva; arc=none smtp.client-ip=115.124.30.111 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="eGWo8Zva" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1718325926; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=BSHGNJJW9QoXcHWB3k8CQMWS0eij0PY1paTcRNlGmA0=; b=eGWo8ZvauAbAiOEB42aoHczSD2QWUGLKEI9iCMrc0DlsBFcIs69CKpdlBOoY+au162myxfeI3n+uVV+4s0bKJxWjlMbmZeyOI9Ue4pg9qbYvbsDQnNBccTqWwBSTUybKXhOKYRDRCUfXDYt70ndnrIjNjkHTb54ldhCJdZiVDWI= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R861e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037067113;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0W8PHSgM_1718325885; Received: from 30.97.56.56(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0W8PHSgM_1718325885) by smtp.aliyun-inc.com; Fri, 14 Jun 2024 08:45:25 +0800 Message-ID: <03b1c415-b86b-482c-ae9d-f8d0730fafbe@linux.alibaba.com> Date: Fri, 14 Jun 2024 08:45:25 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: shmem: fix getting incorrect lruvec when replacing a shmem folio To: Yosry Ahmed Cc: akpm@linux-foundation.org, hughd@google.com, hannes@cmpxchg.org, nphamcs@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <3c11000dd6c1df83015a8321a859e9775ebbc23e.1718266112.git.baolin.wang@linux.alibaba.com> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2024/6/14 06:24, Yosry Ahmed wrote: > On Thu, Jun 13, 2024 at 1:21 AM Baolin Wang > wrote: >> >> 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 serious >> 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:0x0 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=0|zone=2|lastcpupid=0x3ffff) >> [ 5241.100323] raw: 17fffe0000040068 fffffdffd6687948 fffffdffd69ae008 0000000000000000 >> [ 5241.100325] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 >> [ 5241.100326] head: 17fffe0000040068 fffffdffd6687948 fffffdffd69ae008 0000000000000000 >> [ 5241.100327] head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 >> [ 5241.100328] head: 17fffe0000000204 fffffdffd6665801 ffffffffffffffff 0000000000000000 >> [ 5241.100329] head: 0000000a00000010 0000000000000000 00000000ffffffff 0000000000000000 >> [ 5241.100330] page dumped because: VM_WARN_ON_ONCE_FOLIO(!memcg && !mem_cgroup_disabled()) >> [ 5241.100338] ------------[ cut here ]------------ >> [ 5241.100339] WARNING: CPU: 19 PID: 78402 at include/linux/memcontrol.h:775 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 migration") >> Signed-off-by: Baolin Wang >> --- >> mm/shmem.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> 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 = shmem_replace_entry(swap_mapping, swap_index, old, new); >> if (!error) { >> - mem_cgroup_migrate(old, new); >> + mem_cgroup_replace_folio(old, new); > > The comment above the definition of mem_cgroup_replace_folio() needs > to be updated with this change. It mentions that it is only used in > replace_page_cache_folio(), which is no longer true. Indeed, will update the related comments in v2. Thanks.