This is a note to let you know that I've just added the patch titled
gfs2: Silence "suspicious RCU usage in gfs2_permission" warning
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
gfs2-silence-suspicious-rcu-usage-in-gfs2_permission.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 22bfd6a4a66458eef633efa2d60760f19c8d8b23
Author: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Date: Mon Oct 30 22:06:05 2023 +0100
gfs2: Silence "suspicious RCU usage in gfs2_permission" warning
[ Upstream commit 074d7306a4fe22fcac0b53f699f92757ab1cee99 ]
Commit 0abd1557e21c added rcu_dereference() for dereferencing ip->i_gl
in gfs2_permission. This now causes lockdep to complain when
gfs2_permission is called in non-RCU context:
WARNING: suspicious RCU usage in gfs2_permission
Switch to rcu_dereference_check() and check for the MAY_NOT_BLOCK flag
to shut up lockdep when we know that dereferencing ip->i_gl is safe.
Fixes: 0abd1557e21c ("gfs2: fix an oops in gfs2_permission")
Reported-by: syzbot+3e5130844b0c0e2b4948@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index eb4bbe1728c06..4e63fbb63151c 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -1866,6 +1866,7 @@ static const char *gfs2_get_link(struct dentry *dentry,
int gfs2_permission(struct mnt_idmap *idmap, struct inode *inode,
int mask)
{
+ int may_not_block = mask & MAY_NOT_BLOCK;
struct gfs2_inode *ip;
struct gfs2_holder i_gh;
struct gfs2_glock *gl;
@@ -1873,14 +1874,14 @@ int gfs2_permission(struct mnt_idmap *idmap, struct inode *inode,
gfs2_holder_mark_uninitialized(&i_gh);
ip = GFS2_I(inode);
- gl = rcu_dereference(ip->i_gl);
+ gl = rcu_dereference_check(ip->i_gl, !may_not_block);
if (unlikely(!gl)) {
/* inode is getting torn down, must be RCU mode */
- WARN_ON_ONCE(!(mask & MAY_NOT_BLOCK));
+ WARN_ON_ONCE(!may_not_block);
return -ECHILD;
}
if (gfs2_glock_is_locked_by_me(gl) == NULL) {
- if (mask & MAY_NOT_BLOCK)
+ if (may_not_block)
return -ECHILD;
error = gfs2_glock_nq_init(gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
if (error)
