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Wed, 11 Jun 2025 09:07:13 -0700 (PDT) MIME-Version: 1.0 References: <20250610181645.45922-1-ryncsn@gmail.com> In-Reply-To: From: Kairui Song Date: Thu, 12 Jun 2025 00:06:56 +0800 X-Gm-Features: AX0GCFt4t_8yDOu11d-KG53Oczm6SR3x8UIXqkMwAnKPuK9iGpQph60ayJCC9M0 Message-ID: Subject: Re: [PATCH v3] mm/shmem, swap: fix softlockup with mTHP swapin To: Baoquan He , Andrew Morton Cc: linux-mm@kvack.org, Hugh Dickins , Baolin Wang , Kemeng Shi , Chris Li , Nhat Pham , Barry Song , Usama Arif , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: EBA4E180014 X-Stat-Signature: fmr51w31zz1sh8fo68m691ucnjncp6jr X-Rspamd-Server: rspam04 X-HE-Tag: 1749658035-338253 X-HE-Meta: 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 KwztXEog 7vb49LK+HxRenZR90zUdFaArFSoZN4PhTgMDCiwi+1zV1crrNNyM5006G2w4rPtfZ0qDVoKn5UyD51dyaVUvmpMEgF+9aXnsGwsvWnjfx4okfPt8sB9mA7owVbL2sxF3aqMvnUeN6LQ04C8ZSQNM2knGLry+ZuqbzEeNjRUWYrgkhXKV1g6hC5lhBlibMswVteqVH1R7pcT0no4UgZvgiHhlrrcg7jsbvv4e6ZjcZiuVtuaIbp0wwRLVNIYwzDDgik8LwDib6zVWVhdDnjkS+FZ0dKz6AyJrpIxGD4MrTZO6FTGByiMYFxvFz1yEvBsCP+yKJAQs8+A2PuD+9u3LpP+ZmnIEiIHK1ZEBXSYidoe6P39NL8ybpyYWB6Q== 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: On Wed, Jun 11, 2025 at 11:33=E2=80=AFAM Baoquan He wrote: > > On 06/11/25 at 02:16am, Kairui Song wrote: > > From: Kairui Song > > > > Following softlockup can be easily reproduced on my test machine with: > > > > echo always > /sys/kernel/mm/transparent_hugepage/hugepages-64kB/enable= d > > swapon /dev/zram0 # zram0 is a 48G swap device > > mkdir -p /sys/fs/cgroup/memory/test > > echo 1G > /sys/fs/cgroup/test/memory.max > > echo $BASHPID > /sys/fs/cgroup/test/cgroup.procs > > while true; do > > dd if=3D/dev/zero of=3D/tmp/test.img bs=3D1M count=3D5120 > > cat /tmp/test.img > /dev/null > > rm /tmp/test.img > > done > > > > Then after a while: > > watchdog: BUG: soft lockup - CPU#0 stuck for 763s! [cat:5787] > > Modules linked in: zram virtiofs > > CPU: 0 UID: 0 PID: 5787 Comm: cat Kdump: loaded Tainted: G = L 6.15.0.orig-gf3021d9246bc-dirty #118 PREEMPT(voluntary)=C2=B7 > > Tainted: [L]=3DSOFTLOCKUP > > Hardware name: Red Hat KVM/RHEL-AV, BIOS 0.0.0 02/06/2015 > > RIP: 0010:mpol_shared_policy_lookup+0xd/0x70 > > Code: e9 b8 b4 ff ff 31 c0 c3 cc cc cc cc 90 90 90 90 90 90 90 90 90 90= 90 90 90 90 90 90 90 66 0f 1f 00 0f 1f 44 00 00 41 54 55 53 <48> 8b 1f 48 = 85 db 74 41 4c 8d 67 08 48 89 fb 48 89 f5 4c 89 e7 e8 > > RSP: 0018:ffffc90002b1fc28 EFLAGS: 00000202 > > RAX: 00000000001c20ca RBX: 0000000000724e1e RCX: 0000000000000001 > > RDX: ffff888118e214c8 RSI: 0000000000057d42 RDI: ffff888118e21518 > > RBP: 000000000002bec8 R08: 0000000000000001 R09: 0000000000000000 > > R10: 0000000000000bf4 R11: 0000000000000000 R12: 0000000000000001 > > R13: 00000000001c20ca R14: 00000000001c20ca R15: 0000000000000000 > > FS: 00007f03f995c740(0000) GS:ffff88a07ad9a000(0000) knlGS:00000000000= 00000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 00007f03f98f1000 CR3: 0000000144626004 CR4: 0000000000770eb0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > PKRU: 55555554 > > Call Trace: > > > > shmem_alloc_folio+0x31/0xc0 > > shmem_swapin_folio+0x309/0xcf0 > > ? filemap_get_entry+0x117/0x1e0 > > ? xas_load+0xd/0xb0 > > ? filemap_get_entry+0x101/0x1e0 > > shmem_get_folio_gfp+0x2ed/0x5b0 > > shmem_file_read_iter+0x7f/0x2e0 > > vfs_read+0x252/0x330 > > ksys_read+0x68/0xf0 > > do_syscall_64+0x4c/0x1c0 > > entry_SYSCALL_64_after_hwframe+0x76/0x7e > > RIP: 0033:0x7f03f9a46991 > > Code: 00 48 8b 15 81 14 10 00 f7 d8 64 89 02 b8 ff ff ff ff eb bd e8 20= ad 01 00 f3 0f 1e fa 80 3d 35 97 10 00 00 74 13 31 c0 0f 05 <48> 3d 00 f0 = ff ff 77 4f c3 66 0f 1f 44 00 00 55 48 89 e5 48 83 ec > > RSP: 002b:00007fff3c52bd28 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 > > RAX: ffffffffffffffda RBX: 0000000000040000 RCX: 00007f03f9a46991 > > RDX: 0000000000040000 RSI: 00007f03f98ba000 RDI: 0000000000000003 > > RBP: 00007fff3c52bd50 R08: 0000000000000000 R09: 00007f03f9b9a380 > > R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000040000 > > R13: 00007f03f98ba000 R14: 0000000000000003 R15: 0000000000000000 > > > > > > The reason is simple, readahead brought some order 0 folio in swap cach= e, > > and the swapin mTHP folio being allocated is in confict with it, so > ^^^typo, conflict > Nice catch, thanks! Hi Andrew, it's only one typo in the commit message here, will you help update the commit message while merging it or should I send a new version?