| Message ID | 20240712031314.2570452-1-linmiaohe@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] mm/hugetlb: fix possible recursive locking detected warning | expand |
> On Jul 12, 2024, at 11:13, Miaohe Lin <linmiaohe@huawei.com> wrote: > > When tries to demote 1G hugetlb folios, a lockdep warning is observed: > > ============================================ > 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 > > but task is already holding lock: > ffffffff8f0a6f48 (&h->resize_lock){+.+.}-{3:3}, at: demote_store+0xae/0x460 > > other info that might help us debug this: > Possible unsafe locking scenario: > > CPU0 > ---- > lock(&h->resize_lock); > lock(&h->resize_lock); > > *** DEADLOCK *** > > May be due to missing lock nesting notation > > 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 > > 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: > <TASK> > 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 > </TASK> > > 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. > > Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support") > Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Muchun Song <muchun.song@linux.dev> Thanks.
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 98c2c1106500..b84da6f6ac40 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -649,6 +649,7 @@ HPAGEFLAG(RawHwpUnreliable, raw_hwp_unreliable) /* Defines one hugetlb page size */ struct hstate { struct mutex resize_lock; + struct lock_class_key resize_key; int next_nid_to_alloc; int next_nid_to_free; unsigned int order; diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 45fd3bc75332..926b89e165bd 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4670,7 +4670,7 @@ void __init hugetlb_add_hstate(unsigned int order) BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE); BUG_ON(order < order_base_2(__NR_USED_SUBPAGE)); h = &hstates[hugetlb_max_hstate++]; - mutex_init(&h->resize_lock); + __mutex_init(&h->resize_lock, "resize mutex", &h->resize_key); h->order = order; h->mask = ~(huge_page_size(h) - 1); for (i = 0; i < MAX_NUMNODES; ++i)
When tries to demote 1G hugetlb folios, a lockdep warning is observed: ============================================ 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 but task is already holding lock: ffffffff8f0a6f48 (&h->resize_lock){+.+.}-{3:3}, at: demote_store+0xae/0x460 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&h->resize_lock); lock(&h->resize_lock); *** DEADLOCK *** May be due to missing lock nesting notation 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 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: <TASK> 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 </TASK> 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. Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> --- v2: move lock_class_key into struct hstate and use __mutex_init per Muchun. Thanks. --- include/linux/hugetlb.h | 1 + mm/hugetlb.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-)