tree f18e494ddb6f5c41e1d2d4b34adf8f3f2fc9dc80
parent 324549fae777b9737ca4002a5c455d52c4dc890b
author Johannes Weiner <hannes@cmpxchg.org> 1565290980 -0400
committer Suren Baghdasaryan <surenb@google.com> 1570212586 -0700

BACKPORT: block: annotate refault stalls from IO submission

psi tracks the time tasks wait for refaulting pages to become
uptodate, but it does not track the time spent submitting the IO. The
submission part can be significant if backing storage is contended or
when cgroup throttling (io.latency) is in effect - a lot of time is
spent in submit_bio(). In that case, we underreport memory pressure.

Annotate submit_bio() to account submission time as memory stall when
the bio is reading userspace workingset pages.

Tested-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

(cherry picked from commit b8e24a9300b0836a9d39f6b20746766b3b81f1bd)

Conflicts:
        include/linux/blk_types.h
        block/bio.c

(1. Manually resolved BIO_WORKINGSET being definition instead of enum.
 2. Add bio_set_flag call into bio_add_page instead of not yet existing
__bio_add_page)

Bug: 141131229
Test: boot and run act test suite
Change-Id: I99cef039844e219f1dc8196feead54b6f5fb26bb
Signed-off-by: Suren Baghdasaryan <surenb@google.com>