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authorMiaohe Lin <linmiaohe@huawei.com>2024-04-07 10:54:56 +0200
committerAndrew Morton <akpm@linux-foundation.org>2024-04-17 00:39:50 +0200
commit1983184c22dd84a4d95a71e5c6775c2638557dc7 (patch)
tree61ae81d40c4b87c60ec197bf5c3f0aee3909b98b /mm/memory-failure.c
parentmm/userfaultfd: allow hugetlb change protection upon poison entry (diff)
downloadlinux-1983184c22dd84a4d95a71e5c6775c2638557dc7.tar.xz
linux-1983184c22dd84a4d95a71e5c6775c2638557dc7.zip
mm/memory-failure: fix deadlock when hugetlb_optimize_vmemmap is enabled
When I did hard offline test with hugetlb pages, below deadlock occurs: ====================================================== WARNING: possible circular locking dependency detected 6.8.0-11409-gf6cef5f8c37f #1 Not tainted ------------------------------------------------------ bash/46904 is trying to acquire lock: ffffffffabe68910 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_slow_dec+0x16/0x60 but task is already holding lock: ffffffffabf92ea8 (pcp_batch_high_lock){+.+.}-{3:3}, at: zone_pcp_disable+0x16/0x40 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (pcp_batch_high_lock){+.+.}-{3:3}: __mutex_lock+0x6c/0x770 page_alloc_cpu_online+0x3c/0x70 cpuhp_invoke_callback+0x397/0x5f0 __cpuhp_invoke_callback_range+0x71/0xe0 _cpu_up+0xeb/0x210 cpu_up+0x91/0xe0 cpuhp_bringup_mask+0x49/0xb0 bringup_nonboot_cpus+0xb7/0xe0 smp_init+0x25/0xa0 kernel_init_freeable+0x15f/0x3e0 kernel_init+0x15/0x1b0 ret_from_fork+0x2f/0x50 ret_from_fork_asm+0x1a/0x30 -> #0 (cpu_hotplug_lock){++++}-{0:0}: __lock_acquire+0x1298/0x1cd0 lock_acquire+0xc0/0x2b0 cpus_read_lock+0x2a/0xc0 static_key_slow_dec+0x16/0x60 __hugetlb_vmemmap_restore_folio+0x1b9/0x200 dissolve_free_huge_page+0x211/0x260 __page_handle_poison+0x45/0xc0 memory_failure+0x65e/0xc70 hard_offline_page_store+0x55/0xa0 kernfs_fop_write_iter+0x12c/0x1d0 vfs_write+0x387/0x550 ksys_write+0x64/0xe0 do_syscall_64+0xca/0x1e0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(pcp_batch_high_lock); lock(cpu_hotplug_lock); lock(pcp_batch_high_lock); rlock(cpu_hotplug_lock); *** DEADLOCK *** 5 locks held by bash/46904: #0: ffff98f6c3bb23f0 (sb_writers#5){.+.+}-{0:0}, at: ksys_write+0x64/0xe0 #1: ffff98f6c328e488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0xf8/0x1d0 #2: ffff98ef83b31890 (kn->active#113){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x100/0x1d0 #3: ffffffffabf9db48 (mf_mutex){+.+.}-{3:3}, at: memory_failure+0x44/0xc70 #4: ffffffffabf92ea8 (pcp_batch_high_lock){+.+.}-{3:3}, at: zone_pcp_disable+0x16/0x40 stack backtrace: CPU: 10 PID: 46904 Comm: bash Kdump: loaded Not tainted 6.8.0-11409-gf6cef5f8c37f #1 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 check_noncircular+0x129/0x140 __lock_acquire+0x1298/0x1cd0 lock_acquire+0xc0/0x2b0 cpus_read_lock+0x2a/0xc0 static_key_slow_dec+0x16/0x60 __hugetlb_vmemmap_restore_folio+0x1b9/0x200 dissolve_free_huge_page+0x211/0x260 __page_handle_poison+0x45/0xc0 memory_failure+0x65e/0xc70 hard_offline_page_store+0x55/0xa0 kernfs_fop_write_iter+0x12c/0x1d0 vfs_write+0x387/0x550 ksys_write+0x64/0xe0 do_syscall_64+0xca/0x1e0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 RIP: 0033:0x7fc862314887 Code: 10 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24 RSP: 002b:00007fff19311268 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 000000000000000c RCX: 00007fc862314887 RDX: 000000000000000c RSI: 000056405645fe10 RDI: 0000000000000001 RBP: 000056405645fe10 R08: 00007fc8623d1460 R09: 000000007fffffff R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000000c R13: 00007fc86241b780 R14: 00007fc862417600 R15: 00007fc862416a00 In short, below scene breaks the lock dependency chain: memory_failure __page_handle_poison zone_pcp_disable -- lock(pcp_batch_high_lock) dissolve_free_huge_page __hugetlb_vmemmap_restore_folio static_key_slow_dec cpus_read_lock -- rlock(cpu_hotplug_lock) Fix this by calling drain_all_pages() instead. This issue won't occur until commit a6b40850c442 ("mm: hugetlb: replace hugetlb_free_vmemmap_enabled with a static_key"). As it introduced rlock(cpu_hotplug_lock) in dissolve_free_huge_page() code path while lock(pcp_batch_high_lock) is already in the __page_handle_poison(). [linmiaohe@huawei.com: extend comment per Oscar] [akpm@linux-foundation.org: reflow block comment] Link: https://lkml.kernel.org/r/20240407085456.2798193-1-linmiaohe@huawei.com Fixes: a6b40850c442 ("mm: hugetlb: replace hugetlb_free_vmemmap_enabled with a static_key") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Jane Chu <jane.chu@oracle.com> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to '')
-rw-r--r--mm/memory-failure.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 9349948f1abf..9e62a00b46dd 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -154,11 +154,23 @@ static int __page_handle_poison(struct page *page)
{
int ret;
- zone_pcp_disable(page_zone(page));
+ /*
+ * zone_pcp_disable() can't be used here. It will
+ * hold pcp_batch_high_lock and dissolve_free_huge_page() might hold
+ * cpu_hotplug_lock via static_key_slow_dec() when hugetlb vmemmap
+ * optimization is enabled. This will break current lock dependency
+ * chain and leads to deadlock.
+ * Disabling pcp before dissolving the page was a deterministic
+ * approach because we made sure that those pages cannot end up in any
+ * PCP list. Draining PCP lists expels those pages to the buddy system,
+ * but nothing guarantees that those pages do not get back to a PCP
+ * queue if we need to refill those.
+ */
ret = dissolve_free_huge_page(page);
- if (!ret)
+ if (!ret) {
+ drain_all_pages(page_zone(page));
ret = take_page_off_buddy(page);
- zone_pcp_enable(page_zone(page));
+ }
return ret;
}