Merge tag 'for-6.12/io_uring-20240922' of git://git.kernel.dk/linux

Pull more io_uring updates from Jens Axboe:
 "Mostly just a set of fixes in here, or little changes that didn't get
  included in the initial pull request. This contains:

   - Move the SQPOLL napi polling outside the submission lock (Olivier)

   - Rename of the "copy buffers" API that got added in the 6.12 merge
     window. There's really no copying going on, it's just referencing
     the buffers. After a bit of consideration, decided that it was
     better to simply rename this to avoid potential confusion (me)

   - Shrink struct io_mapped_ubuf from 48 to 32 bytes, by changing it to
     start + len tracking rather than having start / end in there, and
     by removing the caching of folio_mask when we can just calculate it
     from folio_shift when we need it (me)

   - Fixes for the SQPOLL affinity checking (me, Felix)

   - Fix for how cqring waiting checks for the presence of task_work.
     Just check it directly rather than check for a specific
     notification mechanism (me)

   - Tweak to how request linking is represented in tracing (me)

   - Fix a syzbot report that deliberately sets up a huge list of
     overflow entries, and then hits rcu stalls when flushing this list.
     Just check for the need to preempt, and drop/reacquire locks in the
     loop. There's no state maintained over the loop itself, and each
     entry is yanked from head-of-list (me)"

* tag 'for-6.12/io_uring-20240922' of git://git.kernel.dk/linux:
  io_uring: check if we need to reschedule during overflow flush
  io_uring: improve request linking trace
  io_uring: check for presence of task_work rather than TIF_NOTIFY_SIGNAL
  io_uring/sqpoll: do the napi busy poll outside the submission block
  io_uring: clean up a type in io_uring_register_get_file()
  io_uring/sqpoll: do not put cpumask on stack
  io_uring/sqpoll: retain test for whether the CPU is valid
  io_uring/rsrc: change ubuf->ubuf_end to length tracking
  io_uring/rsrc: get rid of io_mapped_ubuf->folio_mask
  io_uring: rename "copy buffers" to "clone buffers"

1 files changed, 10 insertions, 13 deletions

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index a7164aa7d13e..33a3d156a85b 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -38,7 +38,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
 static const struct io_mapped_ubuf dummy_ubuf = {
 	/* set invalid range, so io_import_fixed() fails meeting it */
 	.ubuf = -1UL,
-	.ubuf_end = 0,
+	.len = UINT_MAX,
 };
 
 int __io_account_mem(struct user_struct *user, unsigned long nr_pages)
@@ -991,16 +991,13 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
 	size = iov->iov_len;
 	/* store original address for later verification */
 	imu->ubuf = (unsigned long) iov->iov_base;
-	imu->ubuf_end = imu->ubuf + iov->iov_len;
+	imu->len = iov->iov_len;
 	imu->nr_bvecs = nr_pages;
 	imu->folio_shift = PAGE_SHIFT;
-	imu->folio_mask = PAGE_MASK;
-	if (coalesced) {
+	if (coalesced)
 		imu->folio_shift = data.folio_shift;
-		imu->folio_mask = ~((1UL << data.folio_shift) - 1);
-	}
 	refcount_set(&imu->refs, 1);
-	off = (unsigned long) iov->iov_base & ~imu->folio_mask;
+	off = (unsigned long) iov->iov_base & ((1UL << imu->folio_shift) - 1);
 	*pimu = imu;
 	ret = 0;
 
@@ -1100,7 +1097,7 @@ int io_import_fixed(int ddir, struct iov_iter *iter,
 	if (unlikely(check_add_overflow(buf_addr, (u64)len, &buf_end)))
 		return -EFAULT;
 	/* not inside the mapped region */
-	if (unlikely(buf_addr < imu->ubuf || buf_end > imu->ubuf_end))
+	if (unlikely(buf_addr < imu->ubuf || buf_end > (imu->ubuf + imu->len)))
 		return -EFAULT;
 
 	/*
@@ -1143,14 +1140,14 @@ int io_import_fixed(int ddir, struct iov_iter *iter,
 			iter->bvec = bvec + seg_skip;
 			iter->nr_segs -= seg_skip;
 			iter->count -= bvec->bv_len + offset;
-			iter->iov_offset = offset & ~imu->folio_mask;
+			iter->iov_offset = offset & ((1UL << imu->folio_shift) - 1);
 		}
 	}
 
 	return 0;
 }
 
-static int io_copy_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx)
+static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx)
 {
 	struct io_mapped_ubuf **user_bufs;
 	struct io_rsrc_data *data;
@@ -1214,9 +1211,9 @@ out_unlock:
  *
  * Since the memory is already accounted once, don't account it again.
  */
-int io_register_copy_buffers(struct io_ring_ctx *ctx, void __user *arg)
+int io_register_clone_buffers(struct io_ring_ctx *ctx, void __user *arg)
 {
-	struct io_uring_copy_buffers buf;
+	struct io_uring_clone_buffers buf;
 	bool registered_src;
 	struct file *file;
 	int ret;
@@ -1234,7 +1231,7 @@ int io_register_copy_buffers(struct io_ring_ctx *ctx, void __user *arg)
 	file = io_uring_register_get_file(buf.src_fd, registered_src);
 	if (IS_ERR(file))
 		return PTR_ERR(file);
-	ret = io_copy_buffers(ctx, file->private_data);
+	ret = io_clone_buffers(ctx, file->private_data);
 	if (!registered_src)
 		fput(file);
 	return ret;