From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Sahkeel Butt <shakeelb@google.com>,
Minchan Kim <minchan@google.com>,
Johannes Weiner <hannes@cmpxchg.org>
Subject: [PATCH] mm: annotate refault stalls from swap_readpage
Date: Thu, 10 Oct 2019 08:21:34 -0700 [thread overview]
Message-ID: <20191010152134.38545-1-minchan@kernel.org> (raw)
From: Minchan Kim <minchan@google.com>
If block device supports rw_page operation, it doesn't submit bio
so 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.
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Minchan Kim <minchan@google.com>
---
mm/page_io.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/mm/page_io.c b/mm/page_io.c
index 24ee600f9131..20147473d4a5 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -22,6 +22,7 @@
#include <linux/writeback.h>
#include <linux/frontswap.h>
#include <linux/blkdev.h>
+#include <linux/psi.h>
#include <linux/uio.h>
#include <linux/sched/task.h>
#include <asm/pgtable.h>
@@ -354,10 +355,14 @@ int swap_readpage(struct page *page, bool synchronous)
struct swap_info_struct *sis = page_swap_info(page);
blk_qc_t qc;
struct gendisk *disk;
+ unsigned long pflags;
VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(PageUptodate(page), page);
+
+ psi_memstall_enter(&pflags);
+
if (frontswap_load(page) == 0) {
SetPageUptodate(page);
unlock_page(page);
@@ -371,7 +376,7 @@ int swap_readpage(struct page *page, bool synchronous)
ret = mapping->a_ops->readpage(swap_file, page);
if (!ret)
count_vm_event(PSWPIN);
- return ret;
+ goto out;
}
ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
@@ -382,7 +387,7 @@ int swap_readpage(struct page *page, bool synchronous)
}
count_vm_event(PSWPIN);
- return 0;
+ goto out;
}
ret = 0;
@@ -418,6 +423,7 @@ int swap_readpage(struct page *page, bool synchronous)
bio_put(bio);
out:
+ psi_memstall_leave(&pflags);
return ret;
}
--
2.23.0.581.g78d2f28ef7-goog
next reply other threads:[~2019-10-10 15:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-10 15:21 Minchan Kim [this message]
2019-10-10 19:17 ` [PATCH] mm: annotate refault stalls from swap_readpage Johannes Weiner
2019-10-10 22:11 ` Minchan Kim
2019-10-11 17:32 ` Shakeel Butt
2019-10-11 21:32 ` Andrew Morton
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