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Message-ID: <20260119235456.1722452-7-axboe@kernel.dk>
Date: Mon, 19 Jan 2026 16:54:29 -0700
From: Jens Axboe <axboe@...nel.dk>
To: io-uring@...r.kernel.org
Cc: brauner@...nel.org,
jannh@...gle.com,
kees@...nel.org,
linux-kernel@...r.kernel.org,
Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 6/7] io_uring: add task fork hook
Called when copy_process() is called to copy state to a new child.
Right now this is just a stub, but will be used shortly to properly
handle fork'ing of task based io_uring restrictions.
Signed-off-by: Jens Axboe <axboe@...nel.dk>
---
include/linux/io_uring.h | 14 +++++++++++++-
include/linux/sched.h | 1 +
io_uring/tctx.c | 25 ++++++++++++++++---------
kernel/fork.c | 5 +++++
4 files changed, 35 insertions(+), 10 deletions(-)
diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index 85fe4e6b275c..d1aa4edfc2a5 100644
--- a/include/linux/io_uring.h
+++ b/include/linux/io_uring.h
@@ -12,6 +12,7 @@ void __io_uring_free(struct task_struct *tsk);
void io_uring_unreg_ringfd(void);
const char *io_uring_get_opcode(u8 opcode);
bool io_is_uring_fops(struct file *file);
+int __io_uring_fork(struct task_struct *tsk);
static inline void io_uring_files_cancel(void)
{
@@ -25,9 +26,16 @@ static inline void io_uring_task_cancel(void)
}
static inline void io_uring_free(struct task_struct *tsk)
{
- if (tsk->io_uring)
+ if (tsk->io_uring || tsk->io_uring_restrict)
__io_uring_free(tsk);
}
+static inline int io_uring_fork(struct task_struct *tsk)
+{
+ if (tsk->io_uring_restrict)
+ return __io_uring_fork(tsk);
+
+ return 0;
+}
#else
static inline void io_uring_task_cancel(void)
{
@@ -46,6 +54,10 @@ static inline bool io_is_uring_fops(struct file *file)
{
return false;
}
+static inline int io_uring_fork(struct task_struct *tsk)
+{
+ return 0;
+}
#endif
#endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index d395f2810fac..9abbd11bb87c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1190,6 +1190,7 @@ struct task_struct {
#ifdef CONFIG_IO_URING
struct io_uring_task *io_uring;
+ struct io_restriction *io_uring_restrict;
#endif
/* Namespaces: */
diff --git a/io_uring/tctx.c b/io_uring/tctx.c
index 5b66755579c0..d4f7698805e4 100644
--- a/io_uring/tctx.c
+++ b/io_uring/tctx.c
@@ -54,16 +54,18 @@ void __io_uring_free(struct task_struct *tsk)
* node is stored in the xarray. Until that gets sorted out, attempt
* an iteration here and warn if any entries are found.
*/
- xa_for_each(&tctx->xa, index, node) {
- WARN_ON_ONCE(1);
- break;
- }
- WARN_ON_ONCE(tctx->io_wq);
- WARN_ON_ONCE(tctx->cached_refs);
+ if (tctx) {
+ xa_for_each(&tctx->xa, index, node) {
+ WARN_ON_ONCE(1);
+ break;
+ }
+ WARN_ON_ONCE(tctx->io_wq);
+ WARN_ON_ONCE(tctx->cached_refs);
- percpu_counter_destroy(&tctx->inflight);
- kfree(tctx);
- tsk->io_uring = NULL;
+ percpu_counter_destroy(&tctx->inflight);
+ kfree(tctx);
+ tsk->io_uring = NULL;
+ }
}
__cold int io_uring_alloc_task_context(struct task_struct *task,
@@ -351,3 +353,8 @@ int io_ringfd_unregister(struct io_ring_ctx *ctx, void __user *__arg,
return i ? i : ret;
}
+
+int __io_uring_fork(struct task_struct *tsk)
+{
+ return 0;
+}
diff --git a/kernel/fork.c b/kernel/fork.c
index b1f3915d5f8e..08a2515380ec 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -97,6 +97,7 @@
#include <linux/kasan.h>
#include <linux/scs.h>
#include <linux/io_uring.h>
+#include <linux/io_uring_types.h>
#include <linux/bpf.h>
#include <linux/stackprotector.h>
#include <linux/user_events.h>
@@ -2129,6 +2130,9 @@ __latent_entropy struct task_struct *copy_process(
#ifdef CONFIG_IO_URING
p->io_uring = NULL;
+ retval = io_uring_fork(p);
+ if (unlikely(retval))
+ goto bad_fork_cleanup_delayacct;
#endif
p->default_timer_slack_ns = current->timer_slack_ns;
@@ -2525,6 +2529,7 @@ __latent_entropy struct task_struct *copy_process(
mpol_put(p->mempolicy);
#endif
bad_fork_cleanup_delayacct:
+ io_uring_free(p);
delayacct_tsk_free(p);
bad_fork_cleanup_count:
dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
--
2.51.0
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