From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 EFB843D7D7F; Mon, 1 Jun 2026 15:07:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780326431; cv=none; b=IhjiVsgW85+M2k8oK5qthM4SIC2xlOKsF2LZGXxiiD/A6OzkmCceObgFH83e7E+mLX5HiWptBsRtyfaL9aKHUapqI8imOMCItZgYx7NZREv4nXQwHffK3mYJB9iOorwzdGRCrSFMfAUbez7BmdIQNOIxl5RhmAGQIkTtozREdis= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780326431; c=relaxed/simple; bh=l24A4xtSXmCG4cWpWE26kMbivFR6YG8PmPI2QvPnYA4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=PEnC8FtEnuVXNOzii2lVZwvJAlXyg/TNrZal7hHNp9FSnRKxvim13rqCwdoe0akRj3grs7E+tF80BChQ1NZeg33ms9PnC5l2r3jXXyCVML9thLKjB8+gDY/PicZauhy9VVw8nUJVmoenjQ00FzdbVig/yHc7YRAOXRmE2mYAYgs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GLLNx4tr; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GLLNx4tr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1DF021F00893; Mon, 1 Jun 2026 15:07:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780326429; bh=4fyrYnBMknGZNZvrg4Jkv5tJrVT1PYSgZLWdGZo8E8E=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=GLLNx4trRl8BW+neKsDlqwr/7K2a3JfqfT6qqpsrw1JKVrCNklaDyGpn7PxankWcl Tj/rbcPSGdZ3/KPlAGxFQ6phAPnKDg2d+bPMLZ0PlNE9QNt0CmLF10qmYB8QRdbnb0 dVxfgKuk4/RJ/o4UKn3lLc9Z40JPYh2tlQamcXwmUECXMii0YysZI23JCj0+4LcckI h5u9qOpub1iAhZwqu1LwY6Py7f7OO3/ON1Mnw5AB8Ur6Xk4LnPRAYneclKkRJ56NsF kp5DRs8ABecaCkS9FS9LxKykevvXjqJTcsabvyc6hZAgyWwHotAXomHwYlCbNoLmuh q1MWATAN5LXww== Message-ID: <52287c46-aba8-4247-9939-4994bd57c4bd@kernel.org> Date: Mon, 1 Jun 2026 17:07:04 +0200 Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [mm?] [arch?] BUG: sleeping function called from invalid context in __tlb_batch_free_encoded_pages To: Will Deacon , syzbot Cc: akpm@linux-foundation.org, aneesh.kumar@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, npiggin@gmail.com, peterz@infradead.org, syzkaller-bugs@googlegroups.com, qi.zheng@linux.dev References: <69f302ff.170a0220.3c4978.0016.GAE@google.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/27/26 14:05, Will Deacon wrote: > I finally got a chance to look at this one... > > On Thu, Apr 30, 2026 at 12:21:35AM -0700, syzbot wrote: >> syzbot found the following issue on: >> >> HEAD commit: dca922e019dd Merge tag 'xsa48x-7.1-tag' of git://git.kerne.. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=11cd6b6c580000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=59da38148f3a3d24 >> dashboard link: https://syzkaller.appspot.com/bug?extid=a169a27b0538ba43e5d3 >> compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 >> >> Unfortunately, I don't have any reproducer for this issue yet. >> >> Downloadable assets: >> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-dca922e0.raw.xz >> vmlinux: https://storage.googleapis.com/syzbot-assets/7b447b1b93a9/vmlinux-dca922e0.xz >> kernel image: https://storage.googleapis.com/syzbot-assets/af7830f5dabf/bzImage-dca922e0.xz >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+a169a27b0538ba43e5d3@syzkaller.appspotmail.com >> >> BUG: sleeping function called from invalid context at mm/mmu_gather.c:142 >> in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 5677, name: rm >> preempt_count: 0, expected: 0 >> RCU nest depth: 1, expected: 0 >> 2 locks held by rm/5677: >> #0: ffff888022c20338 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock include/linux/mmap_lock.h:536 [inline] >> #0: ffff888022c20338 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x22c/0xa10 mm/mmap.c:1308 >> #1: ffffffff8e7e54e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire.constprop.0+0x7/0x30 include/linux/rcupdate.h:300 >> CPU: 1 UID: 0 PID: 5677 Comm: rm Not tainted syzkaller #0 PREEMPT(full) >> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 >> Call Trace: >> >> __dump_stack lib/dump_stack.c:94 [inline] >> dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 >> __might_resched.cold+0x1ec/0x232 kernel/sched/core.c:9162 >> __tlb_batch_free_encoded_pages+0x11e/0x280 mm/mmu_gather.c:142 >> tlb_batch_pages_flush mm/mmu_gather.c:151 [inline] > > ... so we're getting deep in the gather code tearing down an mm, where > we free the unmapped pages but we're somehow inside an RCU read-side > critical section. > > The last report on the sysbot dashboard is from 30th April, which > coincides with 99ebc509eef5 ("mm: memcontrol: fix rcu unbalance in > get_non_dying_memcg_end()") landing upstream. Unfortunately, there's no > reproducer available to test that concretely but it looks like we can > end up in there via the page freeing path. So hopefully this is fixed. Yes, sounds reasonable. -- Cheers, David