| Message ID | 1385120110-13240-1-git-send-email-luis.henriques@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/include/linux/fs.h b/include/linux/fs.h index 17fd887..65b8b69 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -925,9 +925,11 @@ static inline loff_t i_size_read(const struct inode *inode) static inline void i_size_write(struct inode *inode, loff_t i_size) { #if BITS_PER_LONG==32 && defined(CONFIG_SMP) + preempt_disable(); write_seqcount_begin(&inode->i_size_seqcount); inode->i_size = i_size; write_seqcount_end(&inode->i_size_seqcount); + preempt_enable(); #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT) preempt_disable(); inode->i_size = i_size;
This is a note to let you know that I have just added a patch titled include/linux/fs.h: disable preempt when acquire i_size_seqcount to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 2127ef25e5778f4878085862ce4b8fc9815e24d5 Mon Sep 17 00:00:00 2001 From: Fan Du <fan.du@windriver.com> Date: Tue, 30 Apr 2013 15:27:27 -0700 Subject: 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 <fan.du@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Zhao Hongjiang <zhaohongjiang@huawei.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- include/linux/fs.h | 2 ++ 1 file changed, 2 insertions(+) -- 1.8.3.2