* [PATCH 1/2] fuse: Move ring queues_refs decrement
2025-10-21 21:33 [PATCH 0/2] fuse: Fix possible memleak at startup with immediate teardown Bernd Schubert
@ 2025-10-21 21:33 ` Bernd Schubert
2025-10-21 21:33 ` [PATCH 2/2] fs/fuse: fix potential memory leak from fuse_uring_cancel Bernd Schubert
1 sibling, 0 replies; 3+ messages in thread
From: Bernd Schubert @ 2025-10-21 21:33 UTC (permalink / raw)
To: Miklos Szeredi; +Cc: Joanne Koong, linux-fsdevel, Jian Huang Li, Bernd Schubert
This is just to avoid code dup with an upcoming commit.
Signed-off-by: Bernd Schubert <bschubert@ddn.com>
---
fs/fuse/dev_uring.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index f6b12aebb8bbe7d255980593b75b5fb5af9c669e..e7c1095b83b11fe46080c24f539df17e70969e21 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -328,7 +328,7 @@ static void fuse_uring_entry_teardown(struct fuse_ring_ent *ent)
{
struct fuse_req *req;
struct io_uring_cmd *cmd;
-
+ ssize_t queue_refs;
struct fuse_ring_queue *queue = ent->queue;
spin_lock(&queue->lock);
@@ -356,15 +356,16 @@ static void fuse_uring_entry_teardown(struct fuse_ring_ent *ent)
if (req)
fuse_uring_stop_fuse_req_end(req);
+
+ queue_refs = atomic_dec_return(&queue->ring->queue_refs);
+ WARN_ON_ONCE(queue_refs < 0);
}
static void fuse_uring_stop_list_entries(struct list_head *head,
struct fuse_ring_queue *queue,
enum fuse_ring_req_state exp_state)
{
- struct fuse_ring *ring = queue->ring;
struct fuse_ring_ent *ent, *next;
- ssize_t queue_refs = SSIZE_MAX;
LIST_HEAD(to_teardown);
spin_lock(&queue->lock);
@@ -381,11 +382,8 @@ static void fuse_uring_stop_list_entries(struct list_head *head,
spin_unlock(&queue->lock);
/* no queue lock to avoid lock order issues */
- list_for_each_entry_safe(ent, next, &to_teardown, list) {
+ list_for_each_entry_safe(ent, next, &to_teardown, list)
fuse_uring_entry_teardown(ent);
- queue_refs = atomic_dec_return(&ring->queue_refs);
- WARN_ON_ONCE(queue_refs < 0);
- }
}
static void fuse_uring_teardown_entries(struct fuse_ring_queue *queue)
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH 2/2] fs/fuse: fix potential memory leak from fuse_uring_cancel
2025-10-21 21:33 [PATCH 0/2] fuse: Fix possible memleak at startup with immediate teardown Bernd Schubert
2025-10-21 21:33 ` [PATCH 1/2] fuse: Move ring queues_refs decrement Bernd Schubert
@ 2025-10-21 21:33 ` Bernd Schubert
1 sibling, 0 replies; 3+ messages in thread
From: Bernd Schubert @ 2025-10-21 21:33 UTC (permalink / raw)
To: Miklos Szeredi
Cc: Joanne Koong, linux-fsdevel, Jian Huang Li, Bernd Schubert,
stable
From: Jian Huang Li <ali@ddn.com>
This issue could be observed sometimes during libfuse xfstests, from
dmseg prints some like "kernel: WARNING: CPU: 4 PID: 0 at
fs/fuse/dev_uring.c:204 fuse_uring_destruct+0x1f5/0x200 [fuse]".
The cause is, if when fuse daemon just submitted
FUSE_IO_URING_CMD_REGISTER SQEs, then umount or fuse daemon quits at
this very early stage. After all uring queues stopped, might have one or
more unprocessed FUSE_IO_URING_CMD_REGISTER SQEs get processed then some
new ring entities are created and added to ent_avail_queue, and
immediately fuse_uring_cancel moved them to ent_in_userspace after SQEs
get canceled. These ring entities were not moved to ent_released, and
stayed in ent_in_userspace when fuse_uring_destruct was called.
One way to solve it would be to also free 'ent_in_userspace' in
fuse_uring_destruct(), but from code point of view it is hard to see why
it is needed. As suggested by Joanne, another solution is to avoid moving
entries in fuse_uring_cancel() to the 'ent_in_userspace' list and just
releasing them directly.
Fixes: b6236c8407cb ("fuse: {io-uring} Prevent mount point hang on fuse-server termination")
Cc: Joanne Koong <joannelkoong@gmail.com>
Cc: <stable@vger.kernel.org> # v6.14
Signed-off-by: Jian Huang Li <ali@ddn.com>
Signed-off-by: Bernd Schubert <bschubert@ddn.com>
---
fs/fuse/dev_uring.c | 21 +++++++++------------
1 file changed, 9 insertions(+), 12 deletions(-)
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index e7c1095b83b11fe46080c24f539df17e70969e21..d88a0c05434a04668241f09f123d5e3a9cc1621d 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -324,7 +324,7 @@ static void fuse_uring_stop_fuse_req_end(struct fuse_req *req)
/*
* Release a request/entry on connection tear down
*/
-static void fuse_uring_entry_teardown(struct fuse_ring_ent *ent)
+static void fuse_uring_entry_teardown(struct fuse_ring_ent *ent, int issue_flags)
{
struct fuse_req *req;
struct io_uring_cmd *cmd;
@@ -352,7 +352,7 @@ static void fuse_uring_entry_teardown(struct fuse_ring_ent *ent)
spin_unlock(&queue->lock);
if (cmd)
- io_uring_cmd_done(cmd, -ENOTCONN, IO_URING_F_UNLOCKED);
+ io_uring_cmd_done(cmd, -ENOTCONN, issue_flags);
if (req)
fuse_uring_stop_fuse_req_end(req);
@@ -383,7 +383,7 @@ static void fuse_uring_stop_list_entries(struct list_head *head,
/* no queue lock to avoid lock order issues */
list_for_each_entry_safe(ent, next, &to_teardown, list)
- fuse_uring_entry_teardown(ent);
+ fuse_uring_entry_teardown(ent, IO_URING_F_UNLOCKED);
}
static void fuse_uring_teardown_entries(struct fuse_ring_queue *queue)
@@ -499,7 +499,7 @@ static void fuse_uring_cancel(struct io_uring_cmd *cmd,
{
struct fuse_ring_ent *ent = uring_cmd_to_ring_ent(cmd);
struct fuse_ring_queue *queue;
- bool need_cmd_done = false;
+ bool teardown = false;
/*
* direct access on ent - it must not be destructed as long as
@@ -508,17 +508,14 @@ static void fuse_uring_cancel(struct io_uring_cmd *cmd,
queue = ent->queue;
spin_lock(&queue->lock);
if (ent->state == FRRS_AVAILABLE) {
- ent->state = FRRS_USERSPACE;
- list_move_tail(&ent->list, &queue->ent_in_userspace);
- need_cmd_done = true;
- ent->cmd = NULL;
+ ent->state = FRRS_TEARDOWN;
+ list_del_init(&ent->list);
+ teardown = true;
}
spin_unlock(&queue->lock);
- if (need_cmd_done) {
- /* no queue lock to avoid lock order issues */
- io_uring_cmd_done(cmd, -ENOTCONN, issue_flags);
- }
+ if (teardown)
+ fuse_uring_entry_teardown(ent, issue_flags);
}
static void fuse_uring_prepare_cancel(struct io_uring_cmd *cmd, int issue_flags,
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread