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authorJosef Bacik <jbacik@fb.com>2017-07-24 15:14:25 -0400
committerDavid Sterba <dsterba@suse.com>2017-08-16 16:12:05 +0200
commit23b5ec74943f44378b68c0edd8e210a86318ea5e (patch)
tree07fc0067812f384350e17660072d864a0a3eec87 /certs/blacklist_nohashes.c
parent8d8aafeea23e2d641460d7e6231361f0322ac058 (diff)
downloadlinux-stable-23b5ec74943f44378b68c0edd8e210a86318ea5e.tar.gz
btrfs: fix readdir deadlock with pagefault
Readdir does dir_emit while under the btree lock. dir_emit can trigger the page fault which means we can deadlock. Fix this by allocating a buffer on opening a directory and copying the readdir into this buffer and doing dir_emit from outside of the tree lock. Thread A readdir <holding tree lock> dir_emit <page fault> down_read(mmap_sem) Thread B mmap write down_write(mmap_sem) page_mkwrite wait_ordered_extents Process C finish_ordered_extent insert_reserved_file_extent try to lock leaf <hang> Signed-off-by: Josef Bacik <jbacik@fb.com> Reviewed-by: David Sterba <dsterba@suse.com> [ copy the deadlock scenario to changelog ] Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'certs/blacklist_nohashes.c')
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