block/psi: remove PSI annotations from direct IO

Direct IO does not operate on the current working set of pages managed
by the kernel, so it should not be accounted as memory stall to PSI
infrastructure.

The block layer and iomap direct IO use bio_iov_iter_get_pages()
to build bios, and they are the only users of it, so to avoid PSI
tracking for them clear out BIO_WORKINGSET flag. Do same for
dio_bio_submit() because fs/direct_io constructs bios by hand directly
calling bio_add_page().

Reported-by: Christoph Hellwig <hch@infradead.org>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bio.c b/block/bio.c
index 56a06f94fb63e5f6bcdeb3ffa6dc18055cc3c364..1cd8a2e79048ddbdca54b9f3153996c30126113c 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1081,6 +1081,9 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
  * fit into the bio, or are requested in @iter, whatever is smaller. If
  * MM encounters an error pinning the requested pages, it stops. Error
  * is returned only if 0 pages could be pinned.
+ *
+ * It's intended for direct IO, so doesn't do PSI tracking, the caller is
+ * responsible for setting BIO_WORKINGSET if necessary.
  */
 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 {
@@ -1105,6 +1108,9 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 
        if (is_bvec)
                bio_set_flag(bio, BIO_NO_PAGE_REF);
+
+       /* don't account direct I/O as memory stall */
+       bio_clear_flag(bio, BIO_WORKINGSET);
        return bio->bi_vcnt ? 0 : ret;
 }
 EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages);

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 2660e744da2d81816f0564836d4d8978796c4b2b..aa1083ecd62392f9c86d8b0d83bb3842f453c458 100644 (file)
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -426,6 +426,8 @@ static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
        unsigned long flags;
 
        bio->bi_private = dio;
+       /* don't account direct I/O as memory stall */
+       bio_clear_flag(bio, BIO_WORKINGSET);
 
        spin_lock_irqsave(&dio->bio_lock, flags);
        dio->refcount++;