The patch titled
vfs: call rcu_barrier after ->kill_sb()
has been added to the -mm tree. Its filename is
vfs-call-rcu_barrier-after-kill_sb.patch
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------------------------------------------------------
Subject: vfs: call rcu_barrier after ->kill_sb()
From: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
In fa0d7e3 ("fs: icache RCU free inodes"), we use rcu free inode instead
of freeing the inode directly. It causes a crash when we rmmod
immediately after we umount the volume[1].
So we need to call rcu_barrier after we kill_sb so that the inode is freed
before we do rmmod. The idea is inspired by Aneesh Kumar. rcu_barrier
will wait for all callbacks to end before preceding. The original patch
was done by Tao Ma, but synchronize_rcu() is not enough here.
1. http://marc.info/?l=linux-fsdevel&m=129680863330185&w=2
Tested-by: Tao Ma <boyu.mt@xxxxxxxxxx>
Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Chris Mason <chris.mason@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/super.c | 5 +++++
1 file changed, 5 insertions(+)
diff -puN fs/super.c~vfs-call-rcu_barrier-after-kill_sb fs/super.c
--- a/fs/super.c~vfs-call-rcu_barrier-after-kill_sb
+++ a/fs/super.c
@@ -177,6 +177,11 @@ void deactivate_locked_super(struct supe
struct file_system_type *fs = s->s_type;
if (atomic_dec_and_test(&s->s_active)) {
fs->kill_sb(s);
+ /*
+ * We need to call rcu_barrier so all the delayed rcu free
+ * inodes are flushed before we release the fs module.
+ */
+ rcu_barrier();
put_filesystem(fs);
put_super(s);
} else {
_
Patches currently in -mm which might be from bharrosh@xxxxxxxxxxx are
vfs-call-rcu_barrier-after-kill_sb.patch
linux-next.patch
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