On Wed, Nov 28, 2018 at 04:42:01PM +0800, Yufen Yu wrote: > 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. > > Signed-off-by: Yufen Yu <yuyufen@xxxxxxxxxx> Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxx> > --- > block/partition-generic.c | 8 +++++--- > include/linux/genhd.h | 2 +- > 2 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/block/partition-generic.c b/block/partition-generic.c > index d3d14e81fb12..5f8db5c5140f 100644 > --- a/block/partition-generic.c > +++ b/block/partition-generic.c > @@ -249,9 +249,10 @@ struct device_type part_type = { > .uevent = part_uevent, > }; > > -static void delete_partition_rcu_cb(struct rcu_head *head) > +static void delete_partition_work_fn(struct work_struct *work) > { > - struct hd_struct *part = container_of(head, struct hd_struct, rcu_head); > + struct hd_struct *part = container_of(to_rcu_work(work), struct hd_struct, > + rcu_work); > > part->start_sect = 0; > part->nr_sects = 0; > @@ -262,7 +263,8 @@ static void delete_partition_rcu_cb(struct rcu_head *head) > void __delete_partition(struct percpu_ref *ref) > { > struct hd_struct *part = container_of(ref, struct hd_struct, ref); > - call_rcu(&part->rcu_head, delete_partition_rcu_cb); > + INIT_RCU_WORK(&part->rcu_work, delete_partition_work_fn); > + queue_rcu_work(system_wq, &part->rcu_work); > } > > /* > diff --git a/include/linux/genhd.h b/include/linux/genhd.h > index 70fc838e6773..0c5ee17b4d88 100644 > --- a/include/linux/genhd.h > +++ b/include/linux/genhd.h > @@ -129,7 +129,7 @@ struct hd_struct { > struct disk_stats dkstats; > #endif > struct percpu_ref ref; > - struct rcu_head rcu_head; > + struct rcu_work rcu_work; > }; > > #define GENHD_FL_REMOVABLE 1 > -- > 2.16.2.dirty >
