From: hui jiao Date: Thu, 5 Jun 2014 03:34:24 +0000 (+0800) Subject: md/raid5: deadlock between retry_aligned_read with barrier io X-Git-Tag: omap-for-v3.16/fixes-against-rc1~58^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2844dc32ea67044b345221067207ce67ffe8da76;p=pandora-kernel.git md/raid5: deadlock between retry_aligned_read with barrier io A chunk aligned read increases counter active_aligned_reads and decreases it after sub-device handle it successfully. But when a read error occurs, the read redispatched by raid5d, and the active_aligned_reads will not be decreased until we can grab a stripe head in retry_aligned_read. Now suppose, a barrier io comes, set conf->quiesce to 2, and wait until both active_stripes and active_aligned_reads are zero. The retried chunk aligned read gets stuck at get_active_stripe waiting until conf->quiesce becomes 0. Retry_aligned_read and barrier io are waiting each other now. One possible solution is that we ignore conf->quiesce, let the retried aligned read finish. I reproduced this deadlock and test this patch on centos6.0 Signed-off-by: NeilBrown --- Reading git-diff-tree failed