From: Tejun Heo Date: Fri, 29 Apr 2011 16:08:37 +0000 (+0200) Subject: workqueue: fix deadlock in worker_maybe_bind_and_lock() X-Git-Tag: v2.6.39-rc6~15^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5035b20fa5cd146b66f5f89619c20a4177fb736d;p=pandora-kernel.git workqueue: fix deadlock in worker_maybe_bind_and_lock() If a rescuer and stop_machine() bringing down a CPU race with each other, they may deadlock on non-preemptive kernel. The CPU won't accept a new task, so the rescuer can't migrate to the target CPU, while stop_machine() can't proceed because the rescuer is holding one of the CPU retrying migration. GCWQ_DISASSOCIATED is never cleared and worker_maybe_bind_and_lock() retries indefinitely. This problem can be reproduced semi reliably while the system is entering suspend. http://thread.gmane.org/gmane.linux.kernel/1122051 A lot of kudos to Thilo-Alexander for reporting this tricky issue and painstaking testing. stable: This affects all kernels with cmwq, so all kernels since and including v2.6.36 need this fix. Signed-off-by: Tejun Heo Reported-by: Thilo-Alexander Ginkel Tested-by: Thilo-Alexander Ginkel Cc: stable@kernel.org --- Reading git-diff-tree failed