Messages in this thread | | | Date | Mon, 2 Feb 2015 15:52:51 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 1/1 linux-next] fs/ufs/super.c: remove CONFIG_SMP/CONFIG_PREEMPT testing |
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On Sun, 1 Feb 2015 12:36:57 +0100 Fabian Frederick <fabf@skynet.be> wrote:
> Let locking subsystem decide on mutex management. > > ... > > --- a/fs/ufs/super.c > +++ b/fs/ufs/super.c > @@ -95,22 +95,18 @@ > > void lock_ufs(struct super_block *sb) > { > -#if defined(CONFIG_SMP) || defined (CONFIG_PREEMPT) > struct ufs_sb_info *sbi = UFS_SB(sb); > > mutex_lock(&sbi->mutex); > sbi->mutex_owner = current; > -#endif > }
Good heavens.
This patch is a bugfix. lock_ufs() is assuming that on non-preempt uniprocessor, the calling code will run atomically up to the matching unlock_ufs().
But that isn't true. The very first site I looked at (ufs_frag_map) does sb_bread() under lock_ufs(. And sb_bread() will call schedule(), very commonly.
The ->mutex_owner stuff is a bit hacky but should work OK.
Care to resend the patch with a more alarming changelog?
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