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authorMikulas Patocka <mpatocka@redhat.com>2010-03-06 02:32:29 +0000
committerAlasdair G Kergon <agk@redhat.com>2010-03-06 02:32:29 +0000
commita97f925a32aad2a37971d7bfb657006acf04e42d (patch)
tree38c74c60f756dd05611138f864340a31f4fc393f /include/linux/dm-ioctl.h
parent8215d6ec5fee1e76545decea2cd73717efb5cb42 (diff)
dm: free dm_io before bio_endio not after
Free the dm_io structure before calling bio_endio() instead of after it, to ensure that the io_pool containing it is not referenced after it is freed. This partially fixes a problem described here https://www.redhat.com/archives/dm-devel/2010-February/msg00109.html thread 1: bio_endio(bio, io_error); /* scheduling happens */ thread 2: close the device remove the device thread 1: free_io(md, io); Thread 2, when removing the device, sees non-empty md->io_pool (because the io hasn't been freed by thread 1 yet) and may crash with BUG in mempool_free. Thread 1 may also crash, when freeing into a nonexisting mempool. To fix this we must make sure that bio_endio() is the last call and the md structure is not accessed afterwards. There is another bio_endio in process_barrier, but it is called from the thread and the thread is destroyed prior to freeing the mempools, so this call is not affected by the bug. A similar bug exists with module unloads - the module may be unloaded immediately after bio_endio - but that is more difficult to fix. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@kernel.org Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'include/linux/dm-ioctl.h')
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