There is no need to allocate aio rings from HIGHMEM because of very
little memory needed here.
Therefore, use GFP_USER flag in find_or_create_page() and get rid of
kmap*() mappings.
Cc: Al Viro <[email protected]>
Cc: Ira Weiny <[email protected]>
Suggested-by: Matthew Wilcox <[email protected]>
Signed-off-by: Fabio M. De Francesco <[email protected]>
---
fs/aio.c | 26 +++++++++-----------------
1 file changed, 9 insertions(+), 17 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index b0b17bd098bb..77e33619de40 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -530,7 +530,7 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
for (i = 0; i < nr_pages; i++) {
struct page *page;
page = find_or_create_page(file->f_mapping,
- i, GFP_HIGHUSER | __GFP_ZERO);
+ i, GFP_USER | __GFP_ZERO);
if (!page)
break;
pr_debug("pid(%d) page[%d]->count=%d\n",
@@ -571,7 +571,7 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
ctx->user_id = ctx->mmap_base;
ctx->nr_events = nr_events; /* trusted copy */
- ring = kmap_atomic(ctx->ring_pages[0]);
+ ring = page_address(ctx->ring_pages[0]);
ring->nr = nr_events; /* user copy */
ring->id = ~0U;
ring->head = ring->tail = 0;
@@ -579,7 +579,6 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
ring->compat_features = AIO_RING_COMPAT_FEATURES;
ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
ring->header_length = sizeof(struct aio_ring);
- kunmap_atomic(ring);
flush_dcache_page(ctx->ring_pages[0]);
return 0;
@@ -682,9 +681,8 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
* we are protected from page migration
* changes ring_pages by ->ring_lock.
*/
- ring = kmap_atomic(ctx->ring_pages[0]);
+ ring = page_address(ctx->ring_pages[0]);
ring->id = ctx->id;
- kunmap_atomic(ring);
return 0;
}
@@ -1025,9 +1023,8 @@ static void user_refill_reqs_available(struct kioctx *ctx)
* against ctx->completed_events below will make sure we do the
* safe/right thing.
*/
- ring = kmap_atomic(ctx->ring_pages[0]);
+ ring = page_address(ctx->ring_pages[0]);
head = ring->head;
- kunmap_atomic(ring);
refill_reqs_available(ctx, head, ctx->tail);
}
@@ -1133,12 +1130,11 @@ static void aio_complete(struct aio_kiocb *iocb)
if (++tail >= ctx->nr_events)
tail = 0;
- ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
+ ev_page = page_address(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
event = ev_page + pos % AIO_EVENTS_PER_PAGE;
*event = iocb->ki_res;
- kunmap_atomic(ev_page);
flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
@@ -1152,10 +1148,9 @@ static void aio_complete(struct aio_kiocb *iocb)
ctx->tail = tail;
- ring = kmap_atomic(ctx->ring_pages[0]);
+ ring = page_address(ctx->ring_pages[0]);
head = ring->head;
ring->tail = tail;
- kunmap_atomic(ring);
flush_dcache_page(ctx->ring_pages[0]);
ctx->completed_events++;
@@ -1215,10 +1210,9 @@ static long aio_read_events_ring(struct kioctx *ctx,
mutex_lock(&ctx->ring_lock);
/* Access to ->ring_pages here is protected by ctx->ring_lock. */
- ring = kmap_atomic(ctx->ring_pages[0]);
+ ring = page_address(ctx->ring_pages[0]);
head = ring->head;
tail = ring->tail;
- kunmap_atomic(ring);
/*
* Ensure that once we've read the current tail pointer, that
@@ -1250,10 +1244,9 @@ static long aio_read_events_ring(struct kioctx *ctx,
avail = min(avail, nr - ret);
avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
- ev = kmap(page);
+ ev = page_address(page);
copy_ret = copy_to_user(event + ret, ev + pos,
sizeof(*ev) * avail);
- kunmap(page);
if (unlikely(copy_ret)) {
ret = -EFAULT;
@@ -1265,9 +1258,8 @@ static long aio_read_events_ring(struct kioctx *ctx,
head %= ctx->nr_events;
}
- ring = kmap_atomic(ctx->ring_pages[0]);
+ ring = page_address(ctx->ring_pages[0]);
ring->head = head;
- kunmap_atomic(ring);
flush_dcache_page(ctx->ring_pages[0]);
pr_debug("%li h%u t%u\n", ret, head, tail);
--
2.40.1
Fabio M. De Francesco wrote:
> There is no need to allocate aio rings from HIGHMEM because of very
> little memory needed here.
>
> Therefore, use GFP_USER flag in find_or_create_page() and get rid of
> kmap*() mappings.
>
> Cc: Al Viro <[email protected]>
> Cc: Ira Weiny <[email protected]>
> Suggested-by: Matthew Wilcox <[email protected]>
> Signed-off-by: Fabio M. De Francesco <[email protected]>
> ---
> fs/aio.c | 26 +++++++++-----------------
> 1 file changed, 9 insertions(+), 17 deletions(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index b0b17bd098bb..77e33619de40 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
[snip]
> @@ -1250,10 +1244,9 @@ static long aio_read_events_ring(struct kioctx *ctx,
> avail = min(avail, nr - ret);
> avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
>
> - ev = kmap(page);
> + ev = page_address(page);
NIT: This might be cleaner to remove the temp variable;
ev = page_address(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
But generally LGTM.
Reviewed-by: Ira Weiny <[email protected]>
On Fri, 09 Jun 2023 16:59:37 +0200, Fabio M. De Francesco wrote:
> There is no need to allocate aio rings from HIGHMEM because of very
> little memory needed here.
>
> Therefore, use GFP_USER flag in find_or_create_page() and get rid of
> kmap*() mappings.
>
>
> [...]
Applied to the vfs.misc branch of the vfs/vfs.git tree.
Patches in the vfs.misc branch should appear in linux-next soon.
Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.
It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.
tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.misc
[1/1] fs/aio: Stop allocating aio rings from HIGHMEM
https://git.kernel.org/vfs/vfs/c/c9657715af76