94a2c3a32b
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: Paul E. McKenney <paulmck@linux.ibm.com> Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
||
|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.