io_uring-6.13-20242901

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Merge tag 'io_uring-6.13-20242901' of git://git.kernel.dk/linux

Pull more io_uring updates from Jens Axboe:

 - Remove a leftover struct from when the cqwait registered waiting was
   transitioned to regions.

 - Fix for an issue introduced in this merge window, where nop->fd might
   be used uninitialized. Ensure it's always set.

 - Add capping of the task_work run in local task_work mode, to prevent
   bursty and long chains from adding too much latency.

 - Work around xa_store() leaving ->head non-NULL if it encounters an
   allocation error during storing. Just a debug trigger, and can go
   away once xa_store() behaves in a more expected way for this
   condition. Not a major thing as it basically requires fault injection
   to trigger it.

 - Fix a few mapping corner cases

 - Fix KCSAN complaint on reading the table size post unlock. Again not
   a "real" issue, but it's easy to silence by just keeping the reading
   inside the lock that protects it.

* tag 'io_uring-6.13-20242901' of git://git.kernel.dk/linux:
  io_uring/tctx: work around xa_store() allocation error issue
  io_uring: fix corner case forgetting to vunmap
  io_uring: fix task_work cap overshooting
  io_uring: check for overflows in io_pin_pages
  io_uring/nop: ensure nop->fd is always initialized
  io_uring: limit local tw done
  io_uring: add io_local_work_pending()
  io_uring/region: return negative -E2BIG in io_create_region()
  io_uring: protect register tracing
  io_uring: remove io_uring_cqwait_reg_arg

include/linux/io_uring_types.h

@@ -336,6 +336,7 @@ struct io_ring_ctx {
 	 */
 	struct {
 		struct llist_head	work_llist;
+		struct llist_head	retry_llist;
 		unsigned long		check_cq;
 		atomic_t		cq_wait_nr;
 		atomic_t		cq_timeouts;

include/uapi/linux/io_uring.h

@@ -873,20 +873,6 @@ enum {
 	IORING_REG_WAIT_TS		= (1U << 0),
 };
 
-/*
- * Argument for IORING_REGISTER_CQWAIT_REG, registering a region of
- * struct io_uring_reg_wait that can be indexed when io_uring_enter(2) is
- * called rather than pass in a wait argument structure separately.
- */
-struct io_uring_cqwait_reg_arg {
-	__u32		flags;
-	__u32		struct_size;
-	__u32		nr_entries;
-	__u32		pad;
-	__u64		user_addr;
-	__u64		pad2[3];
-};
-
 /*
  * Argument for io_uring_enter(2) with
  * IORING_GETEVENTS | IORING_ENTER_EXT_ARG_REG set, where the actual argument

io_uring/io_uring.c

@@ -121,6 +121,7 @@
 
 #define IO_COMPL_BATCH			32
 #define IO_REQ_ALLOC_BATCH		8
+#define IO_LOCAL_TW_DEFAULT_MAX		20
 
 struct io_defer_entry {
 	struct list_head	list;
@@ -1255,12 +1256,14 @@ static void __cold io_move_task_work_from_local(struct io_ring_ctx *ctx)
 	struct llist_node *node = llist_del_all(&ctx->work_llist);
 
 	__io_fallback_tw(node, false);
+	node = llist_del_all(&ctx->retry_llist);
+	__io_fallback_tw(node, false);
 }
 
 static bool io_run_local_work_continue(struct io_ring_ctx *ctx, int events,
 				       int min_events)
 {
-	if (llist_empty(&ctx->work_llist))
+	if (!io_local_work_pending(ctx))
 		return false;
 	if (events < min_events)
 		return true;
@@ -1269,8 +1272,29 @@ static bool io_run_local_work_continue(struct io_ring_ctx *ctx, int events,
 	return false;
 }
 
+static int __io_run_local_work_loop(struct llist_node **node,
+				    struct io_tw_state *ts,
+				    int events)
+{
+	int ret = 0;
+
+	while (*node) {
+		struct llist_node *next = (*node)->next;
+		struct io_kiocb *req = container_of(*node, struct io_kiocb,
+						    io_task_work.node);
+		INDIRECT_CALL_2(req->io_task_work.func,
+				io_poll_task_func, io_req_rw_complete,
+				req, ts);
+		*node = next;
+		if (++ret >= events)
+			break;
+	}
+
+	return ret;
+}
+
 static int __io_run_local_work(struct io_ring_ctx *ctx, struct io_tw_state *ts,
-			       int min_events)
+			       int min_events, int max_events)
 {
 	struct llist_node *node;
 	unsigned int loops = 0;
@@ -1281,25 +1305,23 @@ static int __io_run_local_work(struct io_ring_ctx *ctx, struct io_tw_state *ts,
 	if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
 		atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
 again:
+	min_events -= ret;
+	ret = __io_run_local_work_loop(&ctx->retry_llist.first, ts, max_events);
+	if (ctx->retry_llist.first)
+		goto retry_done;
+
 	/*
 	 * llists are in reverse order, flip it back the right way before
 	 * running the pending items.
 	 */
 	node = llist_reverse_order(llist_del_all(&ctx->work_llist));
-	while (node) {
+	ret += __io_run_local_work_loop(&node, ts, max_events - ret);
-		struct llist_node *next = node->next;
+	ctx->retry_llist.first = node;
-		struct io_kiocb *req = container_of(node, struct io_kiocb,
-						    io_task_work.node);
-		INDIRECT_CALL_2(req->io_task_work.func,
-				io_poll_task_func, io_req_rw_complete,
-				req, ts);
-		ret++;
-		node = next;
-	}
 	loops++;
 
 	if (io_run_local_work_continue(ctx, ret, min_events))
 		goto again;
+retry_done:
 	io_submit_flush_completions(ctx);
 	if (io_run_local_work_continue(ctx, ret, min_events))
 		goto again;
@@ -1313,18 +1335,20 @@ static inline int io_run_local_work_locked(struct io_ring_ctx *ctx,
 {
 	struct io_tw_state ts = {};
 
-	if (llist_empty(&ctx->work_llist))
+	if (!io_local_work_pending(ctx))
 		return 0;
-	return __io_run_local_work(ctx, &ts, min_events);
+	return __io_run_local_work(ctx, &ts, min_events,
+					max(IO_LOCAL_TW_DEFAULT_MAX, min_events));
 }
 
-static int io_run_local_work(struct io_ring_ctx *ctx, int min_events)
+static int io_run_local_work(struct io_ring_ctx *ctx, int min_events,
+			     int max_events)
 {
 	struct io_tw_state ts = {};
 	int ret;
 
 	mutex_lock(&ctx->uring_lock);
-	ret = __io_run_local_work(ctx, &ts, min_events);
+	ret = __io_run_local_work(ctx, &ts, min_events, max_events);
 	mutex_unlock(&ctx->uring_lock);
 	return ret;
 }
@@ -2328,9 +2352,9 @@ static int io_wake_function(struct wait_queue_entry *curr, unsigned int mode,
 
 int io_run_task_work_sig(struct io_ring_ctx *ctx)
 {
-	if (!llist_empty(&ctx->work_llist)) {
+	if (io_local_work_pending(ctx)) {
 		__set_current_state(TASK_RUNNING);
-		if (io_run_local_work(ctx, INT_MAX) > 0)
+		if (io_run_local_work(ctx, INT_MAX, IO_LOCAL_TW_DEFAULT_MAX) > 0)
 			return 0;
 	}
 	if (io_run_task_work() > 0)
@@ -2459,7 +2483,7 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
 {
 	if (unlikely(READ_ONCE(ctx->check_cq)))
 		return 1;
-	if (unlikely(!llist_empty(&ctx->work_llist)))
+	if (unlikely(io_local_work_pending(ctx)))
 		return 1;
 	if (unlikely(task_work_pending(current)))
 		return 1;
@@ -2493,8 +2517,9 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, u32 flags,
 
 	if (!io_allowed_run_tw(ctx))
 		return -EEXIST;
-	if (!llist_empty(&ctx->work_llist))
+	if (io_local_work_pending(ctx))
-		io_run_local_work(ctx, min_events);
+		io_run_local_work(ctx, min_events,
+				  max(IO_LOCAL_TW_DEFAULT_MAX, min_events));
 	io_run_task_work();
 
 	if (unlikely(test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq)))
@@ -2564,8 +2589,8 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, u32 flags,
 		 * If we got woken because of task_work being processed, run it
 		 * now rather than let the caller do another wait loop.
 		 */
-		if (!llist_empty(&ctx->work_llist))
+		if (io_local_work_pending(ctx))
-			io_run_local_work(ctx, nr_wait);
+			io_run_local_work(ctx, nr_wait, nr_wait);
 		io_run_task_work();
 
 		/*
@@ -3077,7 +3102,7 @@ static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
 
 	if ((ctx->flags & IORING_SETUP_DEFER_TASKRUN) &&
 	    io_allowed_defer_tw_run(ctx))
-		ret |= io_run_local_work(ctx, INT_MAX) > 0;
+		ret |= io_run_local_work(ctx, INT_MAX, INT_MAX) > 0;
 	ret |= io_cancel_defer_files(ctx, tctx, cancel_all);
 	mutex_lock(&ctx->uring_lock);
 	ret |= io_poll_remove_all(ctx, tctx, cancel_all);
@@ -3158,7 +3183,7 @@ __cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
 		io_run_task_work();
 		io_uring_drop_tctx_refs(current);
 		xa_for_each(&tctx->xa, index, node) {
-			if (!llist_empty(&node->ctx->work_llist)) {
+			if (io_local_work_pending(node->ctx)) {
 				WARN_ON_ONCE(node->ctx->submitter_task &&
 					     node->ctx->submitter_task != current);
 				goto end_wait;

io_uring/io_uring.h

@@ -347,9 +347,14 @@ static inline int io_run_task_work(void)
 	return ret;
 }
 
+static inline bool io_local_work_pending(struct io_ring_ctx *ctx)
+{
+	return !llist_empty(&ctx->work_llist) || !llist_empty(&ctx->retry_llist);
+}
+
 static inline bool io_task_work_pending(struct io_ring_ctx *ctx)
 {
-	return task_work_pending(current) || !llist_empty(&ctx->work_llist);
+	return task_work_pending(current) || io_local_work_pending(ctx);
 }
 
 static inline void io_tw_lock(struct io_ring_ctx *ctx, struct io_tw_state *ts)
@@ -484,6 +489,6 @@ enum {
 static inline bool io_has_work(struct io_ring_ctx *ctx)
 {
 	return test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq) ||
-	       !llist_empty(&ctx->work_llist);
+	       io_local_work_pending(ctx);
 }
 #endif

io_uring/memmap.c

@@ -73,6 +73,8 @@ void *io_pages_map(struct page ***out_pages, unsigned short *npages,
 	ret = io_mem_alloc_compound(pages, nr_pages, size, gfp);
 	if (!IS_ERR(ret))
 		goto done;
+	if (nr_pages == 1)
+		goto fail;
 
 	ret = io_mem_alloc_single(pages, nr_pages, size, gfp);
 	if (!IS_ERR(ret)) {
@@ -81,7 +83,7 @@ void *io_pages_map(struct page ***out_pages, unsigned short *npages,
 		*npages = nr_pages;
 		return ret;
 	}
-
+fail:
 	kvfree(pages);
 	*out_pages = NULL;
 	*npages = 0;
@@ -136,7 +138,12 @@ struct page **io_pin_pages(unsigned long uaddr, unsigned long len, int *npages)
 	struct page **pages;
 	int ret;
 
-	end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	if (check_add_overflow(uaddr, len, &end))
+		return ERR_PTR(-EOVERFLOW);
+	if (check_add_overflow(end, PAGE_SIZE - 1, &end))
+		return ERR_PTR(-EOVERFLOW);
+
+	end = end >> PAGE_SHIFT;
 	start = uaddr >> PAGE_SHIFT;
 	nr_pages = end - start;
 	if (WARN_ON_ONCE(!nr_pages))
@@ -229,7 +236,7 @@ int io_create_region(struct io_ring_ctx *ctx, struct io_mapped_region *mr,
 	if (!reg->size || reg->mmap_offset || reg->id)
 		return -EINVAL;
 	if ((reg->size >> PAGE_SHIFT) > INT_MAX)
-		return E2BIG;
+		return -E2BIG;
 	if ((reg->user_addr | reg->size) & ~PAGE_MASK)
 		return -EINVAL;
 	if (check_add_overflow(reg->user_addr, reg->size, &end))

io_uring/nop.c

@@ -35,10 +35,14 @@ int io_nop_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		nop->result = READ_ONCE(sqe->len);
 	else
 		nop->result = 0;
-	if (nop->flags & IORING_NOP_FIXED_FILE)
+	if (nop->flags & IORING_NOP_FILE)
 		nop->fd = READ_ONCE(sqe->fd);
+	else
+		nop->fd = -1;
 	if (nop->flags & IORING_NOP_FIXED_BUFFER)
 		nop->buffer = READ_ONCE(sqe->buf_index);
+	else
+		nop->buffer = -1;
 	return 0;
 }
 

io_uring/register.c

@@ -905,9 +905,10 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
 
 	mutex_lock(&ctx->uring_lock);
 	ret = __io_uring_register(ctx, opcode, arg, nr_args);
-	mutex_unlock(&ctx->uring_lock);
+
 	trace_io_uring_register(ctx, opcode, ctx->file_table.data.nr,
 				ctx->buf_table.nr, ret);
+	mutex_unlock(&ctx->uring_lock);
 	if (!use_registered_ring)
 		fput(file);
 	return ret;

io_uring/tctx.c

@@ -47,8 +47,19 @@ static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx,
 void __io_uring_free(struct task_struct *tsk)
 {
 	struct io_uring_task *tctx = tsk->io_uring;
+	struct io_tctx_node *node;
+	unsigned long index;
 
-	WARN_ON_ONCE(!xa_empty(&tctx->xa));
+	/*
+	 * Fault injection forcing allocation errors in the xa_store() path
+	 * can lead to xa_empty() returning false, even though no actual
+	 * 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);