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 250B51993B1 for ; Wed, 26 Feb 2025 07:23:03 +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=1740554587; cv=none; b=XzaCqC3C+tf17S2nb639WaF439WSIFZ2Py/7sMinQwQqdF22q1DtDLueVAn6uOHPuaBAPtyIijR/ovzAuJC/uHNeLUEYeiEXkU0hNhGQ7pCXQ8KwicAiT/0zJ7y+sN+dsqRhEbwg0Ry0yxxWt77d1U3VmiFRqrxP3y0/hkTFjek= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740554587; c=relaxed/simple; bh=eHGaW29Cr2Hlr/1eF6CZ4olB+Jsv5yiB7eZxMMiiz0U=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=A7JwXF95OF9SR57hOTSdQLWawXdYLKWvPIph8XAtBLb2VmGDF5WNZBMzGbf+VsM+DX+SaxECYdEfzZvbd283pVSWBTc+Z/AfXJQhrtir214szo02ZP0hQxg63XFhE31u76mri4wolZfvTpeGQ1SJTXLOZbQqNNwZoSVEPhsaKzo= 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=t8LDdl1j; 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="t8LDdl1j" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1740554581; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=Qsij7OF84wNUFWpZiJMKkhiePiHWb5NpTxQGGeVUXXg=; b=t8LDdl1jCUX0VOh+Myjv3sLKHxG3/sinFkFAWDsHtZf5tzx+xTJv6rB9lHdD0dl61Gbh50UyZimkQQMDTpoibI/aJJIBZwMwYA10226iSubwZyhD3ktihgNG5sGrPo0NwwE5mq0URF54cFHH5woT8dulHINeQ0Pso/uKQUiFIIw= Received: from 30.74.144.124(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0WQHJRGw_1740554579 cluster:ay36) by smtp.aliyun-inc.com; Wed, 26 Feb 2025 15:23:00 +0800 Message-ID: Date: Wed, 26 Feb 2025 15:22:58 +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: Softlockup when test shmem swapout-swapin and compaction To: Liu Shixin , "linux-mm@kvack.org" , Linux Kernel Mailing List Cc: Barry Song , David Hildenbrand , Hugh Dickins , Kefeng Wang , Lance Yang , Matthew Wilcox , Ryan Roberts , Andrew Morton , Zi Yan References: <28546fb4-5210-bf75-16d6-43e1f8646080@huawei.com> From: Baolin Wang In-Reply-To: <28546fb4-5210-bf75-16d6-43e1f8646080@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Add Zi. On 2025/2/26 15:03, Liu Shixin wrote: > Hi all, > > I found a softlockup when testing shmem large folio swapout-swapin and compaction: > > watchdog: BUG: soft lockup - CPU#30 stuck for 179s! [folio_swap:4714] > Modules linked in: zram xt_MASQUERADE nf_conntrack_netlink nfnetlink iptable_nat xt_addrtype iptable_filter ip_tantel_rapl_msr intel_rapl_common intel_uncore_frequency_common skx_edac_common nfit libnvdimm kvm_intel kvm rapl cixt4 mbcache jbd2 sr_mod cdrom ata_generic ata_piix virtio_net net_failover ghash_clmulni_intel libata sha512_ssse3 > CPU: 30 UID: 0 PID: 4714 Comm: folio_swap Kdump: loaded Tainted: G L 6.14.0-rc4-next-20250225+ #2 > Tainted: [L]=SOFTLOCKUP > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 > RIP: 0010:xas_load+0x5d/0xc0 > Code: 08 48 d3 ea 83 e2 3f 89 d0 48 83 c0 04 48 8b 44 c6 08 48 89 73 18 48 89 c1 83 e1 03 48 83 f9 02 75 08 48 3d > RSP: 0000:ffffadf142f1ba60 EFLAGS: 00000293 > RAX: ffffe524cc4f6700 RBX: ffffadf142f1ba90 RCX: 0000000000000000 > RDX: 0000000000000011 RSI: ffff9a3e058acb68 RDI: ffffadf142f1ba90 > RBP: fffffffffffffffe R08: ffffadf142f1bb50 R09: 0000000000000392 > R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000011 > R13: ffffadf142f1bb48 R14: ffff9a3e04e9c588 R15: 0000000000000000 > FS: 00007fd957666740(0000) GS:ffff9a41ac0e5000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fd922860000 CR3: 000000025c360001 CR4: 0000000000772ef0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > PKRU: 55555554 > Call Trace: > > ? watchdog_timer_fn+0x1c9/0x250 > ? __pfx_watchdog_timer_fn+0x10/0x10 > ? __hrtimer_run_queues+0x10e/0x250 > ? hrtimer_interrupt+0xfb/0x240 > ? __sysvec_apic_timer_interrupt+0x4e/0xe0 > ? sysvec_apic_timer_interrupt+0x68/0x90 > > > ? asm_sysvec_apic_timer_interrupt+0x16/0x20 > ? xas_load+0x5d/0xc0 > xas_find+0x153/0x1a0 > find_get_entries+0x73/0x280 > shmem_undo_range+0x1fc/0x640 > shmem_evict_inode+0x109/0x270 > evict+0x107/0x240 > ? fsnotify_destroy_marks+0x25/0x180 > ? _atomic_dec_and_lock+0x35/0x50 > __dentry_kill+0x71/0x190 > dput+0xd1/0x190 > __fput+0x128/0x2a0 > task_work_run+0x57/0x90 > syscall_exit_to_user_mode+0x1cb/0x1e0 > do_syscall_64+0x67/0x170 > entry_SYSCALL_64_after_hwframe+0x76/0x7e > RIP: 0033:0x7fd95776eb8b > > If CONFIG_DEBUG_VM is enabled, we will meet VM_BUG_ON_FOLIO(!folio_test_locked(folio)) in > shmem_add_to_page_cache() too. It seems that the problem is related to memory migration or > compaction which is necessary for reproduction, although without a clear why. > > To reproduce the problem, we need firstly a zram device as swap backend, and then run the > reproduction program. The reproduction program consists of three parts: > 1. A process constantly changes the status of shmem large folio by these interfaces: > /sys/kernel/mm/transparent_hugepage/hugepages-/shmem_enabled > 2. A process constantly echo 1 > /proc/sys/vm/compact_memory > 3. A process constantly alloc/free/swapout/swapin shmem large folios. > > I'm not sure whether the first process is necessary but the second and third are. In addition, > I tried hacking to modify compaction_alloc to return NULL, and the problem disappeared, > so I guess the problem is in migration. > > The problem is different with https://lore.kernel.org/all/1738717785.im3r5g2vxc.none@localhost/ > since I have confirmed this porblem still existed after merge the fixed patch. Could you check if your version includes Zi's fix[1]? Not sure if it's related to the shmem large folio split. [1] https://lore.kernel.org/all/AF487A7A-F685-485D-8D74-756C843D6F0A@nvidia.com/