mm/page_io.c: annotate refault stalls from swap_readpage
authorMinchan Kim <minchan@google.com>
Sun, 1 Dec 2019 01:58:29 +0000 (17:58 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sun, 1 Dec 2019 20:59:11 +0000 (12:59 -0800)
commit937790699be9c8100e5358625e7dfa8b32bd33f2
tree7a86cce7da2bc4023ee9c313c7ba04e5534f72b9
parentdd33d29a19ad81205bfd1d011674b9ed28327e36
mm/page_io.c: annotate refault stalls from swap_readpage

If a block device supports rw_page operation, it doesn't submit bios so
the annotation in submit_bio() for refault stall doesn't work.  It
happens with zram in android, especially swap read path which could
consume CPU cycle for decompress.  It is also a problem for zswap which
uses frontswap.

Annotate swap_readpage() to account the synchronous IO overhead to
prevent underreport memory pressure.

[akpm@linux-foundation.org: add comment, per Johannes]
Link: http://lkml.kernel.org/r/20191010152134.38545-1-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/page_io.c