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From: Muchun Song In-Reply-To: <20240712031314.2570452-1-linmiaohe@huawei.com> Date: Fri, 12 Jul 2024 16:21:52 +0800 Cc: Andrew Morton , Linux-MM , LKML Content-Transfer-Encoding: quoted-printable Message-Id: References: <20240712031314.2570452-1-linmiaohe@huawei.com> To: Miaohe Lin X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 04700A001F X-Stat-Signature: f1kxo9yyoig7p581r8b7o95np7ughybk X-Rspam-User: X-HE-Tag: 1720772552-991185 X-HE-Meta: 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 CD5eN/eX bdai7P/OhbUlW4jIMAHua/CcGn/Ik3poaRon+ia6kNqNS5q4vfgFviH939Ho0kqLwMdkjkeCD82sd/qCLs+ju/IFln2LbEx5cmpBjenQdq6H1UxDswX4Y/Ye9G39tYY1fOWjZDu3t+Khat8ODNiOGeHkn62D3zXYxG60GoZomyeUkx7ys9krAZjuxuqPspFDVYGTsrv3Bpan6gYVUSHqzRfq3mxZ5VQw1mf6s 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 Jul 12, 2024, at 11:13, Miaohe Lin wrote: >=20 > When tries to demote 1G hugetlb folios, a lockdep warning is observed: >=20 > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > WARNING: possible recursive locking detected > 6.10.0-rc6-00452-ga4d0275fa660-dirty #79 Not tainted > -------------------------------------------- > bash/710 is trying to acquire lock: > ffffffff8f0a7850 (&h->resize_lock){+.+.}-{3:3}, at: = demote_store+0x244/0x460 >=20 > but task is already holding lock: > ffffffff8f0a6f48 (&h->resize_lock){+.+.}-{3:3}, at: = demote_store+0xae/0x460 >=20 > other info that might help us debug this: > Possible unsafe locking scenario: >=20 > CPU0 > ---- > lock(&h->resize_lock); > lock(&h->resize_lock); >=20 > *** DEADLOCK *** >=20 > May be due to missing lock nesting notation >=20 > 4 locks held by bash/710: > #0: ffff8f118439c3f0 (sb_writers#5){.+.+}-{0:0}, at: = ksys_write+0x64/0xe0 > #1: ffff8f11893b9e88 (&of->mutex#2){+.+.}-{3:3}, at: = kernfs_fop_write_iter+0xf8/0x1d0 > #2: ffff8f1183dc4428 (kn->active#98){.+.+}-{0:0}, at: = kernfs_fop_write_iter+0x100/0x1d0 > #3: ffffffff8f0a6f48 (&h->resize_lock){+.+.}-{3:3}, at: = demote_store+0xae/0x460 >=20 > stack backtrace: > CPU: 3 PID: 710 Comm: bash Not tainted = 6.10.0-rc6-00452-ga4d0275fa660-dirty #79 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS = rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 > Call Trace: > > dump_stack_lvl+0x68/0xa0 > __lock_acquire+0x10f2/0x1ca0 > lock_acquire+0xbe/0x2d0 > __mutex_lock+0x6d/0x400 > demote_store+0x244/0x460 > kernfs_fop_write_iter+0x12c/0x1d0 > vfs_write+0x380/0x540 > ksys_write+0x64/0xe0 > do_syscall_64+0xb9/0x1d0 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7fa61db14887 > RSP: 002b:00007ffc56c48358 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 > RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fa61db14887 > RDX: 0000000000000002 RSI: 000055a030050220 RDI: 0000000000000001 > RBP: 000055a030050220 R08: 00007fa61dbd1460 R09: 000000007fffffff > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 > R13: 00007fa61dc1b780 R14: 00007fa61dc17600 R15: 00007fa61dc16a00 > >=20 > Lockdep considers this an AA deadlock because the different = resize_lock > mutexes reside in the same lockdep class, but this is a false = positive. > Place them in distinct classes to avoid these warnings. >=20 > Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support") > Signed-off-by: Miaohe Lin Acked-by: Muchun Song Thanks.