[PATCH AUTOSEL 6.11 065/244] vfs: use RCU in ilookup

Sasha Levin
2024-09-25T11:39:17Z

From: Mateusz Guzik <mjguzik@gmail.com>

[ Upstream commit 122381a46954ad592ee93d7da2bef5074b396247 ]

A soft lockup in ilookup was reported when stress-testing a 512-way
system [1] (see [2] for full context) and it was verified that not
taking the lock shifts issues back to mm.

[1] https://lore.kernel.org/linux-mm/56865e57-c250-44da-9713-cf1404595bcc@amd.com/
[2] https://lore.kernel.org/linux-mm/d2841226-e27b-4d3d-a578-63587a3aa4f3@amd.com/

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240715071324.265879-1-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/inode.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index d1a098e7d4087..a2af540102d7a 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1574,9 +1574,7 @@ struct inode *ilookup(struct super_block *sb, unsigned long ino)
struct hlist_head *head = inode_hashtable + hash(sb, ino);
struct inode *inode;
again:
- spin_lock(&inode_hash_lock);
- inode = find_inode_fast(sb, head, ino, true);
- spin_unlock(&inode_hash_lock);
+ inode = find_inode_fast(sb, head, ino, false);

if (inode) {
if (IS_ERR(inode))
--
2.43.0