Commit 14f27939 authored by Committed by Jens Axboe
loop: Flush possible running bios when loop device is released.
When there are still queued bios and reference count drops to zero, loop device must flush all queued bios. Otherwise it can lead to situation that caller closes the device, but some bios are still running and endio() function call later OOpses when uses unallocated mempool. This happens for example when running dm-crypt over loop, here is typical oops backtrace: Oops: 0000 [#1] PREEMPT SMP EIP is at mempool_free+0x12/0x6b ... crypt_dec_pending+0x50/0x54 [dm_crypt] crypt_endio+0x9f/0xa7 [dm_crypt] crypt_endio+0x0/0xa7 [dm_crypt] bio_endio+0x2b/0x2e loop_thread+0x37a/0x3b1 do_lo_send_aops+0x0/0x165 autoremove_wake_function+0x0/0x33 loop_thread+0x0/0x3b1 kthread+0x3b/0x61 kthread+0x0/0x61 kernel_thread_helper+0x7/0x10 (But crash is reproducible with different dm targets running over loop device too.) Patch fixes it by flushing the bios in release call, reusing the flush mechanism for switching backing store. Signed-off-by: Milan Broz <email@example.com> Signed-off-by: Jens Axboe <firstname.lastname@example.org>
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