On Tue, Jan 10, 2012 at 2:05 AM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
>
> I tested Dave's patch and the bug can still be easily reproduced.
>
> And that's to be expected, as the intermediate "being on the lru"
> state that Dave's patch eliminates doesn't play a fundamental part in
> the mechanism of the livelock. It does eliminate one trylock, but
> that's not the one critical to this bug (removing it is a very good
> idea anyway).
>
> The critical trylock here is the one in dentry_kill() which tries to
> lock the parent.
Ok. Here's your patch munged for current -git. You've got most of a
changelog, can you send this out with the right subject and a
sign-off, and re-test with the current git just to make sure.
Al, do you want to handle this or should I take it directly? I'm
assuming nobody has any objections to Miklos' patch?
Linus
fs/dcache.c | 8 +++++---
include/linux/dcache.h | 1 +
2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 3c6d3113a255..6477af24ff0d 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -243,6 +243,7 @@ static void dentry_lru_add(struct dentry *dentry)
static void __dentry_lru_del(struct dentry *dentry)
{
list_del_init(&dentry->d_lru);
+ dentry->d_flags &= ~DCACHE_SHRINK_LIST;
dentry->d_sb->s_nr_dentry_unused--;
dentry_stat.nr_unused--;
}
@@ -806,6 +807,7 @@ relock:
spin_unlock(&dentry->d_lock);
} else {
list_move_tail(&dentry->d_lru, &tmp);
+ dentry->d_flags |= DCACHE_SHRINK_LIST;
spin_unlock(&dentry->d_lock);
if (!--count)
break;
@@ -1098,11 +1100,11 @@ resume:
/*
* move only zero ref count dentries to the dispose list.
*/
- if (!dentry->d_count) {
+ if (dentry->d_count) {
+ dentry_lru_del(dentry);
+ } else if(!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
dentry_lru_move_list(dentry, dispose);
found++;
- } else {
- dentry_lru_del(dentry);
}
/*
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index a47bda5f76db..31f73220e7d7 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -203,6 +203,7 @@ struct dentry_operations {
#define DCACHE_CANT_MOUNT 0x0100
#define DCACHE_GENOCIDE 0x0200
+#define DCACHE_SHRINK_LIST 0x0400
#define DCACHE_NFSFS_RENAMED 0x1000
/* this dentry has been "silly renamed" and has to be deleted on the last
