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Howlett" Cc: lkp@lists.01.org, lkp@intel.com, Andrew Morton , David Hildenbrand , Davidlohr Bueso , "Matthew Wilcox (Oracle)" , Linux Memory Management List , linux-kernel@vger.kernel.org, kernel test robot , Hugh Dickins Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665131707; a=rsa-sha256; cv=none; b=gXrzTFmMbBxaPD634RNgX4YdRX4m1svbnUOJ/8FATbrMItOjMKmIk9+7UZbnQmhucAKDlf GJw32ulNiIluFo97eSDtKls4enGtdsbaav9i0wxlIcCVTMvxR2e2I9VvyILyecj83okmwE ePDZIdqXygnBD65A8e5SrymQ1cLPZ8k= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=YPZ1qIrB; spf=pass (imf29.hostedemail.com: domain of yuzhao@google.com designates 209.85.222.48 as permitted sender) smtp.mailfrom=yuzhao@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665131707; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=+QB2YstNNdejbNNlPhcJ29xpu8+gZThb0NwnVVXxC6U=; b=IFt147IwkN0Y0KF6Af+qGKaxOCVRsnWW4kb9/LV4/uA+PKdLPJuoE/0NW3JimR+Mw4F9hW 5V532bx4+Yf9bkoBQ3QY7EWb7PbdWsUUx4OqJVD36xI4NExnvUuJYJWcvGWYyxysaCzAcP 04sQ0yy/H039Hp1AErJt/3KGRsa8xHE= X-Stat-Signature: tcdd3w78ayyew6mpe9k8qsyaruebnmgq X-Rspamd-Queue-Id: DAE31120013 Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=YPZ1qIrB; spf=pass (imf29.hostedemail.com: domain of yuzhao@google.com designates 209.85.222.48 as permitted sender) smtp.mailfrom=yuzhao@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam08 X-Rspam-User: X-HE-Tag: 1665131707-146653 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: On Thu, Oct 6, 2022 at 6:47 PM Yu Zhao wrote: > > On Wed, Oct 5, 2022 at 9:30 AM kernel test robot wrote: > > > > > > Greeting, > > > > FYI, we noticed the following commit (built with gcc-11): > > > > commit: 763ecb035029f500d7e6dc99acd1ad299b7726a1 ("mm: remove the vma linked list") > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master > > > > in testcase: trinity > > version: trinity-static-i386-x86_64-1c734c75-1_2020-01-06 > > with following parameters: > > > > runtime: 300s > > group: group-03 > > > > test-description: Trinity is a linux system call fuzz tester. > > test-url: http://codemonkey.org.uk/projects/trinity/ > > > > > > on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G > > > > caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): > > > > > > > > If you fix the issue, kindly add following tag > > | Reported-by: kernel test robot > > | Link: https://lore.kernel.org/r/202210052318.5ad10912-oliver.sang@intel.com > > > > > > [ 63.390267][ T5018] ------------[ cut here ]------------ > > [ 63.391875][ T5018] kernel BUG at mm/mmap.c:3167! > > [ 63.393264][ T5018] invalid opcode: 0000 [#1] SMP PTI > > [ 63.394501][ T5018] CPU: 1 PID: 5018 Comm: trinity-c1 Not tainted 6.0.0-rc3-00284-g763ecb035029 #1 > > [ 63.396050][ T5018] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-4 04/01/2014 > > [ 63.397726][ T5018] RIP: 0010:exit_mmap (mm/mmap.c:3167 (discriminator 1)) > > Thanks, Oliver. > > The attached dmesg doesn't say much. My guess is the oom reaper jumped > in between > > mmap_read_unlock(mm); > > /* > * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper > * because the memory has been already freed. > */ > set_bit(MMF_OOM_SKIP, &mm->flags); > mmap_write_lock(mm); > > It seems to me we need to hold the lock for write all the time. But > there is probably a reason we didn't do it in the first place. Apparently this is safe: I checked all places that change VMAs and none of them can race with the above (oom reaper was a red herring).