• Yufen Yu's avatar
    block: use rcu_work instead of call_rcu to avoid sleep in softirq · f3631a8b
    Yufen Yu authored
    commit 94a2c3a32b62e868dc1e3d854326745a7f1b8c7a upstream.
    
    We recently got a stack by syzkaller like this:
    
    BUG: sleeping function called from invalid context at mm/slab.h:361
    in_atomic(): 1, irqs_disabled(): 0, pid: 6644, name: blkid
    INFO: lockdep is turned off.
    CPU: 1 PID: 6644 Comm: blkid Not tainted 4.4.163-514.55.6.9.x86_64+ #76
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
     0000000000000000 5ba6a6b879e50c00 ffff8801f6b07b10 ffffffff81cb2194
     0000000041b58ab3 ffffffff833c7745 ffffffff81cb2080 5ba6a6b879e50c00
     0000000000000000 0000000000000001 0000000000000004 0000000000000000
    Call Trace:
     <IRQ>  [<ffffffff81cb2194>] __dump_stack lib/dump_stack.c:15 [inline]
     <IRQ>  [<ffffffff81cb2194>] dump_stack+0x114/0x1a0 lib/dump_stack.c:51
     [<ffffffff8129a981>] ___might_sleep+0x291/0x490 kernel/sched/core.c:7675
     [<ffffffff8129ac33>] __might_sleep+0xb3/0x270 kernel/sched/core.c:7637
     [<ffffffff81794c13>] slab_pre_alloc_hook mm/slab.h:361 [inline]
     [<ffffffff81794c13>] slab_alloc_node mm/slub.c:2610 [inline]
     [<ffffffff81794c13>] slab_alloc mm/slub.c:2692 [inline]
     [<ffffffff81794c13>] kmem_cache_alloc_trace+0x2c3/0x5c0 mm/slub.c:2709
     [<ffffffff81cbe9a7>] kmalloc include/linux/slab.h:479 [inline]
     [<ffffffff81cbe9a7>] kzalloc include/linux/slab.h:623 [inline]
     [<ffffffff81cbe9a7>] kobject_uevent_env+0x2c7/0x1150 lib/kobject_uevent.c:227
     [<ffffffff81cbf84f>] kobject_uevent+0x1f/0x30 lib/kobject_uevent.c:374
     [<ffffffff81cbb5b9>] kobject_cleanup lib/kobject.c:633 [inline]
     [<ffffffff81cbb5b9>] kobject_release+0x229/0x440 lib/kobject.c:675
     [<ffffffff81cbb0a2>] kref_sub include/linux/kref.h:73 [inline]
     [<ffffffff81cbb0a2>] kref_put include/linux/kref.h:98 [inline]
     [<ffffffff81cbb0a2>] kobject_put+0x72/0xd0 lib/kobject.c:692
     [<ffffffff8216f095>] put_device+0x25/0x30 drivers/base/core.c:1237
     [<ffffffff81c4cc34>] delete_partition_rcu_cb+0x1d4/0x2f0 block/partition-generic.c:232
     [<ffffffff813c08bc>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
     [<ffffffff813c08bc>] rcu_do_batch kernel/rcu/tree.c:2705 [inline]
     [<ffffffff813c08bc>] invoke_rcu_callbacks kernel/rcu/tree.c:2973 [inline]
     [<ffffffff813c08bc>] __rcu_process_callbacks kernel/rcu/tree.c:2940 [inline]
     [<ffffffff813c08bc>] rcu_process_callbacks+0x59c/0x1c70 kernel/rcu/tree.c:2957
     [<ffffffff8120f509>] __do_softirq+0x299/0xe20 kernel/softirq.c:273
     [<ffffffff81210496>] invoke_softirq kernel/softirq.c:350 [inline]
     [<ffffffff81210496>] irq_exit+0x216/0x2c0 kernel/softirq.c:391
     [<ffffffff82c2cd7b>] exiting_irq arch/x86/include/asm/apic.h:652 [inline]
     [<ffffffff82c2cd7b>] smp_apic_timer_interrupt+0x8b/0xc0 arch/x86/kernel/apic/apic.c:926
     [<ffffffff82c2bc25>] apic_timer_interrupt+0xa5/0xb0 arch/x86/entry/entry_64.S:746
     <EOI>  [<ffffffff814cbf40>] ? audit_kill_trees+0x180/0x180
     [<ffffffff8187d2f7>] fd_install+0x57/0x80 fs/file.c:626
     [<ffffffff8180989e>] do_sys_open+0x45e/0x550 fs/open.c:1043
     [<ffffffff818099c2>] SYSC_open fs/open.c:1055 [inline]
     [<ffffffff818099c2>] SyS_open+0x32/0x40 fs/open.c:1050
     [<ffffffff82c299e1>] entry_SYSCALL_64_fastpath+0x1e/0x9a
    
    In softirq context, we call rcu callback function delete_partition_rcu_cb(),
    which may allocate memory by kzalloc with GFP_KERNEL flag. If the
    allocation cannot be satisfied, it may sleep. However, That is not allowed
    in softirq contex.
    
    Although we found this problem on linux 4.4, the latest kernel version
    seems to have this problem as well. And it is very similar to the
    previous one:
    	https://lkml.org/lkml/2018/7/9/391
    
    Fix it by using RCU workqueue, which allows sleep.
    Reviewed-by: default avatarPaul E. McKenney <paulmck@linux.ibm.com>
    Signed-off-by: default avatarYufen Yu <yuyufen@huawei.com>
    Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    f3631a8b
genhd.h 23.4 KB