• Miaohe Lin's avatar
    mm/memory-failure: fix deadlock when hugetlb_optimize_vmemmap is enabled · 1983184c
    Miaohe Lin authored
    When I did hard offline test with hugetlb pages, below deadlock occurs:
    
    ======================================================
    WARNING: possible circular locking dependency detected
    6.8.0-11409-gf6cef5f8 #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-gf6cef5f8 #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 a6b40850 ("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: a6b40850 ("mm: hugetlb: replace hugetlb_free_vmemmap_enabled with a static_key")
    Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
    Acked-by: default avatarOscar Salvador <osalvador@suse.de>
    Reviewed-by: default avatarJane Chu <jane.chu@oracle.com>
    Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    1983184c
memory-failure.c 74.2 KB