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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 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 X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 80CBD180005 X-Stat-Signature: x83b8z7xehhkpr64qk56p3swgbrbmj6g X-Rspam-User: X-HE-Tag: 1740554586-539217 X-HE-Meta: U2FsdGVkX18R6JHZvvAOjEhGLYJj/TV2P8P+yhkJgfsNPolD1eKmY/Krzz7SdBXa+t6Zj3Om+DAQDRSmQX6DAO2k1E4ZJXozJK0WTuDSPdGtetyefEohm+t/0t9x6oEJxgA3d7krEmQqEP5Bl3RAW++x5HGH/lhnR0A5HKCwiOcVNKG374Eg0rDDk7oo0ZJ1mCeSk2NIqOfkX1KXFrMlaEJQf+kht+VerxCmunIhHibyeqZvFurKQzLuNev5d/pXraoaswe8+36NDmrH03EnT8UKSLSKTVUzSnU7rQjxLNBtXFd/Ju3Fm0OGWmdCGdcEGMT5h3SmUHcDjlRL9Q+wRZnVcSDBiqK2CrjcMAizagmV4pnzJspD9c2nDKTG/bfB9cWFg0vH4okQeroJLksdUI6P9PBZFA60vK2BqA9XYTDILTiywzo6PWtkScDyG2WWMSSNXHGcpuCUOag0BRFwgVaqGi/QboZ7VVV5IlGGCg/hz27OAVNOOOlv5IAzf9oorEj9wsUbpXxvjG9gkzRWZgioNOH103+vLIGTX/bpLJYeEKuizu3dW1JUN2B1tg2zx7NxpJbKQMRZvO66A3j02UGcV0BP+/R5gV/44vAo+aZfVV5bYOAcwW4VmfiRSKQPaFPiw3iam/uBaKnkjHE+dskAyHqWBaCnsBl3LB/xnM/v75vWIrfBI4OB4NY/nriWL1eQBk+dzFf/ukDIo8gW+w4quXsJ3Qv4yik4YrNgFmHdm2J7j7ep3WnLmk3KNhKjlheY5qVV9UsdfloQtLslUp9MBSJtAJtREkEIbDvrxXIlbatDDcTWvjmCJMd6w5k5uyzAbeqgonAvpY8KQ1PToh3CIpZNm+2ruFNZzSMMD+9UP0M5WIGGxR8O7QKgVBkKHnXwY/INv3jpz6N4tEFl7kxJMUF0ZKJ/U9s5jNTpNe/jAS+LxjJwu1N6j52JOfBPtsXNQrRBP5i/4nYwP+S x10bBZC4 93NUFLbG+ABaRKysHWlLjQj+z7Gfd1gXKeARSnNDkflWZYw3gGxgSb8FAQ7lJF/QLkGliMALoeS0+mwXHds9YP1flN8QAwJX9Di266GdyT0eQuJt62Hb0QFEdmNyy7zSKBl7q7bUkDcqlrTd0OHIPGAte2vmfmDHpgScgc67xU8FJz8gHwgh7w6cU9+OC4509YNynAxGAuliCj2Tp6TlXc9XIMcETUh2txnI1bL+f+jzYr+8Nm6p+/Btq87z1mBcclWwkX/bG//Pc27DXcZ+Cg4+jpEzhB4tMBSmC0q+031m5Z4zJwoEX2N4p/prKYh68CJcFP6hneQ9rkYlE09P0IyHJPw== 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: List-Subscribe: List-Unsubscribe: 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/