From: Wojciech Lukowicz <wlukowicz01@xxxxxxxxx>
[ Upstream commit b4a72c0589fdea6259720375426179888969d6a2 ]
When removing provided buffers, io_buffer structs are not being disposed
of, leading to a memory leak. They can't be freed individually, because
they are allocated in page-sized groups. They need to be added to some
free list instead, such as io_buffers_cache. All callers already hold
the lock protecting it, apart from when destroying buffers, so had to
extend the lock there.
Fixes: cc3cec8367cb ("io_uring: speedup provided buffer handling")
Signed-off-by: Wojciech Lukowicz <wlukowicz01@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230401195039.404909-2-wlukowicz01@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
io_uring/io_uring.c | 2 +-
io_uring/kbuf.c | 5 ++++-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index a4e9dbc7b67a8..add5cff7952c5 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2722,8 +2722,8 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
io_eventfd_unregister(ctx);
io_alloc_cache_free(&ctx->apoll_cache, io_apoll_cache_free);
io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
- mutex_unlock(&ctx->uring_lock);
io_destroy_buffers(ctx);
+ mutex_unlock(&ctx->uring_lock);
if (ctx->sq_creds)
put_cred(ctx->sq_creds);
if (ctx->submitter_task)
diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
index 0fdcc0adbdbcc..a90c820ce99e1 100644
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -228,11 +228,14 @@ static int __io_remove_buffers(struct io_ring_ctx *ctx,
return i;
}
+ /* protects io_buffers_cache */
+ lockdep_assert_held(&ctx->uring_lock);
+
while (!list_empty(&bl->buf_list)) {
struct io_buffer *nxt;
nxt = list_first_entry(&bl->buf_list, struct io_buffer, list);
- list_del(&nxt->list);
+ list_move(&nxt->list, &ctx->io_buffers_cache);
if (++i == nbufs)
return i;
cond_resched();
--
2.39.2
