io_uring/net: make page accounting more consistent

Make network page accounting more consistent with how buffer
registration is working, i.e. account all memory to ctx->user.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4aacfe64bbb81b27f9ecf5d5c219c69a07e5aa56.1658742118.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

io_uring/net.c

@@ -985,7 +985,7 @@ int io_sendzc(struct io_kiocb *req, unsigned int issue_flags)
 					  &msg.msg_iter);
 		if (unlikely(ret))
 			return ret;
-		ret = mm_account_pinned_pages(&notif->uarg.mmp, zc->len);
+		ret = io_notif_account_mem(notif, zc->len);
 		if (unlikely(ret))
 			return ret;
 	}

io_uring/notif.c

@@ -14,12 +14,10 @@ static void __io_notif_complete_tw(struct callback_head *cb)
 	struct io_notif *notif = container_of(cb, struct io_notif, task_work);
 	struct io_rsrc_node *rsrc_node = notif->rsrc_node;
 	struct io_ring_ctx *ctx = notif->ctx;
-	struct mmpin *mmp = &notif->uarg.mmp;
 
-	if (mmp->user) {
-		atomic_long_sub(mmp->num_pg, &mmp->user->locked_vm);
-		free_uid(mmp->user);
-		mmp->user = NULL;
+	if (notif->account_pages && ctx->user) {
+		__io_unaccount_mem(ctx->user, notif->account_pages);
+		notif->account_pages = 0;
 	}
 	if (likely(notif->task)) {
 		io_put_task(notif->task, 1);
@@ -121,6 +119,7 @@ struct io_notif *io_alloc_notif(struct io_ring_ctx *ctx,
 		notif->ctx = ctx;
 		notif->uarg.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
 		notif->uarg.callback = io_uring_tx_zerocopy_callback;
+		notif->account_pages = 0;
 	}
 
 	notif->seq = slot->seq++;

io_uring/notif.h

@@ -5,6 +5,8 @@
 #include <net/sock.h>
 #include <linux/nospec.h>
 
+#include "rsrc.h"
+
 #define IO_NOTIF_SPLICE_BATCH	32
 #define IORING_MAX_NOTIF_SLOTS (1U << 10)
 
@@ -23,6 +25,8 @@ struct io_notif {
 	/* hook into ctx->notif_list and ctx->notif_list_locked */
 	struct list_head	cache_node;
 
+	unsigned long		account_pages;
+
 	union {
 		struct callback_head	task_work;
 		struct work_struct	commit_work;
@@ -85,3 +89,18 @@ static inline void io_notif_slot_flush_submit(struct io_notif_slot *slot,
 	}
 	io_notif_slot_flush(slot);
 }
+
+static inline int io_notif_account_mem(struct io_notif *notif, unsigned len)
+{
+	struct io_ring_ctx *ctx = notif->ctx;
+	unsigned nr_pages = (len >> PAGE_SHIFT) + 2;
+	int ret;
+
+	if (ctx->user) {
+		ret = __io_account_mem(ctx->user, nr_pages);
+		if (ret)
+			return ret;
+		notif->account_pages += nr_pages;
+	}
+	return 0;
+}

io_uring/rsrc.c

@@ -44,17 +44,13 @@ void io_rsrc_refs_drop(struct io_ring_ctx *ctx)
 	}
 }
 
-static inline void __io_unaccount_mem(struct user_struct *user,
-				      unsigned long nr_pages)
-{
-	atomic_long_sub(nr_pages, &user->locked_vm);
-}
-
-static inline int __io_account_mem(struct user_struct *user,
-				   unsigned long nr_pages)
+int __io_account_mem(struct user_struct *user, unsigned long nr_pages)
 {
 	unsigned long page_limit, cur_pages, new_pages;
 
+	if (!nr_pages)
+		return 0;
+
 	/* Don't allow more pages than we can safely lock */
 	page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
 

io_uring/rsrc.h

@@ -169,4 +169,13 @@ static inline u64 *io_get_tag_slot(struct io_rsrc_data *data, unsigned int idx)
 
 int io_rsrc_update(struct io_kiocb *req, unsigned int issue_flags);
 int io_rsrc_update_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+
+int __io_account_mem(struct user_struct *user, unsigned long nr_pages);
+
+static inline void __io_unaccount_mem(struct user_struct *user,
+				      unsigned long nr_pages)
+{
+	atomic_long_sub(nr_pages, &user->locked_vm);
+}
+
 #endif