60eb34ec55
Kernel crashed when run fio in a RAID5 backend bcache device, the call trace is bellow: [ 440.012034] kernel BUG at block/blk-ioc.c:146! [ 440.012696] invalid opcode: 0000 [#1] SMP NOPTI [ 440.026537] CPU: 2 PID: 2205 Comm: md127_raid5 Not tainted 4.15.0 #8 [ 440.027441] Hardware name: HP ProLiant MicroServer Gen8, BIOS J06 07/16 /2015 [ 440.028615] RIP: 0010:put_io_context+0x8b/0x90 [ 440.029246] RSP: 0018:ffffa8c882b43af8 EFLAGS: 00010246 [ 440.029990] RAX: 0000000000000000 RBX: ffffa8c88294fca0 RCX: 0000000000 0f4240 [ 440.031006] RDX: 0000000000000004 RSI: 0000000000000286 RDI: ffffa8c882 94fca0 [ 440.032030] RBP: ffffa8c882b43b10 R08: 0000000000000003 R09: ffff949cb8 0c1700 [ 440.033206] R10: 0000000000000104 R11: 000000000000b71c R12: 00000000000 01000 [ 440.034222] R13: 0000000000000000 R14: ffff949cad84db70 R15: ffff949cb11 bd1e0 [ 440.035239] FS: 0000000000000000(0000) GS:ffff949cba280000(0000) knlGS: 0000000000000000 [ 440.060190] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 440.084967] CR2: 00007ff0493ef000 CR3: 00000002f1e0a002 CR4: 00000000001 606e0 [ 440.110498] Call Trace: [ 440.135443] bio_disassociate_task+0x1b/0x60 [ 440.160355] bio_free+0x1b/0x60 [ 440.184666] bio_put+0x23/0x30 [ 440.208272] search_free+0x23/0x40 [bcache] [ 440.231448] cached_dev_write_complete+0x31/0x70 [bcache] [ 440.254468] closure_put+0xb6/0xd0 [bcache] [ 440.277087] request_endio+0x30/0x40 [bcache] [ 440.298703] bio_endio+0xa1/0x120 [ 440.319644] handle_stripe+0x418/0x2270 [raid456] [ 440.340614] ? load_balance+0x17b/0x9c0 [ 440.360506] handle_active_stripes.isra.58+0x387/0x5a0 [raid456] [ 440.380675] ? __release_stripe+0x15/0x20 [raid456] [ 440.400132] raid5d+0x3ed/0x5d0 [raid456] [ 440.419193] ? schedule+0x36/0x80 [ 440.437932] ? schedule_timeout+0x1d2/0x2f0 [ 440.456136] md_thread+0x122/0x150 [ 440.473687] ? wait_woken+0x80/0x80 [ 440.491411] kthread+0x102/0x140 [ 440.508636] ? find_pers+0x70/0x70 [ 440.524927] ? kthread_associate_blkcg+0xa0/0xa0 [ 440.541791] ret_from_fork+0x35/0x40 [ 440.558020] Code: c2 48 00 5b 41 5c 41 5d 5d c3 48 89 c6 4c 89 e7 e8 bb c2 48 00 48 8b 3d bc 36 4b 01 48 89 de e8 7c f7 e0 ff 5b 41 5c 41 5d 5d c3 <0f> 0b 0f 1f 00 0f 1f 44 00 00 55 48 8d 47 b8 48 89 e5 41 57 41 [ 440.610020] RIP: put_io_context+0x8b/0x90 RSP: ffffa8c882b43af8 [ 440.628575] ---[ end trace a1fd79d85643a73e ]-- All the crash issue happened when a bypass IO coming, in such scenario s->iop.bio is pointed to the s->orig_bio. In search_free(), it finishes the s->orig_bio by calling bio_complete(), and after that, s->iop.bio became invalid, then kernel would crash when calling bio_put(). Maybe its upper layer's faulty, since bio should not be freed before we calling bio_put(), but we'd better calling bio_put() first before calling bio_complete() to notify upper layer ending this bio. This patch moves bio_complete() under bio_put() to avoid kernel crash. [mlyle: fixed commit subject for character limits] Reported-by: Matthias Ferdinand <bcache@mfedv.net> Tested-by: Matthias Ferdinand <bcache@mfedv.net> Signed-off-by: Tang Junhui <tang.junhui@zte.com.cn> Reviewed-by: Michael Lyle <mlyle@lyle.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.