From: Fan Du Date: Tue, 30 Apr 2013 22:27:27 +0000 (-0700) Subject: include/linux/fs.h: disable preempt when acquire i_size_seqcount write lock X-Git-Tag: v3.2.53~52 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=40b3183d5a1c19369c3c15b9bce144f2ccf330f0;p=pandora-kernel.git include/linux/fs.h: disable preempt when acquire i_size_seqcount write lock commit 74e3d1e17b2e11d175970b85acd44f5927000ba2 upstream. Two rt tasks bind to one CPU core. The higher priority rt task A preempts a lower priority rt task B which has already taken the write seq lock, and then the higher priority rt task A try to acquire read seq lock, it's doomed to lockup. rt task A with lower priority: call write i_size_write rt task B with higher priority: call sync, and preempt task A write_seqcount_begin(&inode->i_size_seqcount); i_size_read inode->i_size = i_size; read_seqcount_begin <-- lockup here... So disable preempt when acquiring every i_size_seqcount *write* lock will cure the problem. Signed-off-by: Fan Du Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed