The use of kmap() and kmap_atomic() are being deprecated in favor of
kmap_local_page().
With kmap_local_page(), the mappings are per thread, CPU local and not
globally visible. Furthermore, the mappings can be acquired from any
context (including interrupts).
Therefore, use kmap_local_page() in aio.c because these mappings are per
thread, CPU local, and not globally visible.
Tested with xfstests on a QEMU + KVM 32-bits VM booting a kernel with
HIGHMEM64GB enabled.
Suggested-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx>
---
I've tested with "./check -g aio". The tests in this group fail 3/26
times, with and without my patch. Therefore, these changes don't introduce
further errors.
fs/aio.c | 32 ++++++++++++++++----------------
1 file changed, 16 insertions(+), 16 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 3c249b938632..343fea0c6d1a 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -567,7 +567,7 @@ 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 = kmap_local_page(ctx->ring_pages[0]);
ring->nr = nr_events; /* user copy */
ring->id = ~0U;
ring->head = ring->tail = 0;
@@ -575,7 +575,7 @@ 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);
+ kunmap_local(ring);
flush_dcache_page(ctx->ring_pages[0]);
return 0;
@@ -678,9 +678,9 @@ 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 = kmap_local_page(ctx->ring_pages[0]);
ring->id = ctx->id;
- kunmap_atomic(ring);
+ kunmap_local(ring);
return 0;
}
@@ -1024,9 +1024,9 @@ 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 = kmap_local_page(ctx->ring_pages[0]);
head = ring->head;
- kunmap_atomic(ring);
+ kunmap_local(ring);
refill_reqs_available(ctx, head, ctx->tail);
}
@@ -1132,12 +1132,12 @@ 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 = kmap_local_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
event = ev_page + pos % AIO_EVENTS_PER_PAGE;
*event = iocb->ki_res;
- kunmap_atomic(ev_page);
+ kunmap_local(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,
@@ -1151,10 +1151,10 @@ static void aio_complete(struct aio_kiocb *iocb)
ctx->tail = tail;
- ring = kmap_atomic(ctx->ring_pages[0]);
+ ring = kmap_local_page(ctx->ring_pages[0]);
head = ring->head;
ring->tail = tail;
- kunmap_atomic(ring);
+ kunmap_local(ring);
flush_dcache_page(ctx->ring_pages[0]);
ctx->completed_events++;
@@ -1214,10 +1214,10 @@ 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 = kmap_local_page(ctx->ring_pages[0]);
head = ring->head;
tail = ring->tail;
- kunmap_atomic(ring);
+ kunmap_local(ring);
/*
* Ensure that once we've read the current tail pointer, that
@@ -1249,10 +1249,10 @@ 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 = kmap_local_page(page);
copy_ret = copy_to_user(event + ret, ev + pos,
sizeof(*ev) * avail);
- kunmap(page);
+ kunmap_local(ev);
if (unlikely(copy_ret)) {
ret = -EFAULT;
@@ -1264,9 +1264,9 @@ static long aio_read_events_ring(struct kioctx *ctx,
head %= ctx->nr_events;
}
- ring = kmap_atomic(ctx->ring_pages[0]);
+ ring = kmap_local_page(ctx->ring_pages[0]);
ring->head = head;
- kunmap_atomic(ring);
+ kunmap_local(ring);
flush_dcache_page(ctx->ring_pages[0]);
pr_debug("%li h%u t%u\n", ret, head, tail);
--
2.36.1
