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Jones" , Mark W , regressions@lists.linux.dev Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 5D046C0007 X-Stat-Signature: 5fg1a5otqbowjxp7te67iwiaup535kfn X-Rspam-User: X-HE-Tag: 1713314012-729204 X-HE-Meta: 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 KaXC5puw 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 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 Tue, Apr 16, 2024 at 5:19=E2=80=AFAM Christian Heusel wrote: > > Hello everyone, > > while rebuilding a few packages in Arch Linux we have recently come > across a regression in the linux kernel which was made visible by a test > failure in libguestfs[0], where the booted kernel showed a Call Trace > like the following one: > > [ 218.738568] CPU: 0 PID: 167 Comm: guestfsd Not tainted 6.7.0-rc4-1-mai= nline-00158-gb5ba474f3f51 #1 bf39861cf50acae7a79c534e25532f28afe4e593^M > [ 218.739007] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS A= rch Linux 1.16.3-1-1 04/01/2014^M > [ 218.739787] RIP: 0010:memcg_page_state+0x9/0x30^M > [ 218.740299] Code: 0d b8 ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 9= 0 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 0f 1f 44 00 00 <= 48> 8b 87 00 06 00 00 48 63 f6 31 d2 48 8b 04 f0 48 85 c0 48 0f 48^M > [ 218.740727] RSP: 0018:ffffb5fa808dfc10 EFLAGS: 00000202^M > [ 218.740862] RAX: 0000000000000000 RBX: ffffb5fa808dfce0 RCX: 000000000= 0000002^M > [ 218.741016] RDX: 0000000000000001 RSI: 0000000000000033 RDI: 000000000= 0000000^M > [ 218.741168] RBP: 0000000000000000 R08: ffff976681ff8000 R09: 000000000= 0000000^M > [ 218.741322] R10: 0000000000000001 R11: ffff9766833f9d00 R12: ffff9766f= fffe780^M > [ 218.742167] R13: 0000000000000000 R14: ffff976680cc1800 R15: ffff97668= 2204d80^M > [ 218.742376] FS: 00007f1479d9f540(0000) GS:ffff9766fbc00000(0000) knlG= S:0000000000000000^M > [ 218.742569] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033^M > [ 218.743256] CR2: 0000000000000600 CR3: 0000000103606000 CR4: 000000000= 0750ef0^M > [ 218.743494] PKRU: 55555554^M > [ 218.743593] Call Trace:^M > [ 218.743733] ^M > [ 218.743847] ? __die+0x23/0x70^M > [ 218.743957] ? page_fault_oops+0x171/0x4e0^M > [ 218.744056] ? free_unref_page+0xf6/0x180^M > [ 218.744458] ? exc_page_fault+0x7f/0x180^M > [ 218.744551] ? asm_exc_page_fault+0x26/0x30^M > [ 218.744684] ? memcg_page_state+0x9/0x30^M > [ 218.744779] zswap_shrinker_count+0x9d/0x110^M > [ 218.744896] do_shrink_slab+0x3a/0x360^M > [ 218.744990] shrink_slab+0xc7/0x3c0^M > [ 218.745609] drop_slab+0x85/0x140^M > [ 218.745691] drop_caches_sysctl_handler+0x7e/0xd0^M > [ 218.745799] proc_sys_call_handler+0x1c0/0x2e0^M > [ 218.745912] vfs_write+0x23d/0x400^M > [ 218.745998] ksys_write+0x6f/0xf0^M > [ 218.746080] do_syscall_64+0x64/0xe0^M > [ 218.746169] ? exit_to_user_mode_prepare+0x132/0x1f0^M > [ 218.746873] entry_SYSCALL_64_after_hwframe+0x6e/0x76^M > > The regression is present in the mainline kernel and also was > independently reported to the redhat bugtracker[1]. > > I have bisected (see log[2]) the regression between v6.9-rc4 and v6.6 > and have landed on the following results (removed unrelated test commit) > as remainders since some of the commits were not buildable for me: > - 7108cc3f765c ("mm: memcg: add per-memcg zswap writeback stat") > - a65b0e7607cc ("zswap: make shrinking memcg-aware") > - b5ba474f3f51 ("zswap: shrink zswap pool based on memory pressure") > > I have decided on good/bad commits with the relevant libguestfs tests, > but I think the reproducer in the redhat bugzilla is simpler (although I > only became aware of it during the bisection and therefore didn't test > it myself): > > LIBGUESTFS_MEMSIZE=3D4096 LIBGUESTFS_DEBUG=3D1 LIBGUESTFS_TRACE=3D1 mak= e -C /build/libguestfs/src/libguestfs-1.52.0/tests -k check TESTS=3Dc-api/t= ests > I have a suspect for the bug: https://lore.kernel.org/all/CAKEwX=3DMWPUf1NMGdn+1AkRdOUf25ifAbPyoP9zppPTx3= U3Tv2Q@mail.gmail.com/ Feel free to fact check me, but let me see if I can reproduce this bug on my own setting based on this analysis and send a fix accordingly :)