diff mbox series

[049/200] mm/swap_state: skip meaningless swap cache readahead when ra_info.win == 0

Message ID 20201215030601.YXwoWTcgy%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [001/200] kthread: add kthread_work tracepoints | expand

Commit Message

Andrew Morton Dec. 15, 2020, 3:06 a.m. UTC 
From: Miaohe Lin <linmiaohe@huawei.com>
Subject: mm/swap_state: skip meaningless swap cache readahead when ra_info.win == 0

swap_ra_info() may leave ra_info untouched in non_swap_entry() case as
page table lock is not held.  In this case, we have ra_info.nr_pte == 0
and it is meaningless to continue with swap cache readahead.  Skip such
ops by init ra_info.win = 1.

[akpm@linux-foundation.org: clean up struct init]
Link: https://lkml.kernel.org/r/20201009133059.58407-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swap_state.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff mbox series

Patch

--- a/mm/swap_state.c~mm-swap_state-skip-meaningless-swap-cache-readahead-when-ra_infowin-==-0
+++ a/mm/swap_state.c
@@ -839,7 +839,9 @@  static struct page *swap_vma_readahead(s
 	swp_entry_t entry;
 	unsigned int i;
 	bool page_allocated;
-	struct vma_swap_readahead ra_info = {0,};
+	struct vma_swap_readahead ra_info = {
+		.win = 1,
+	};
 
 	swap_ra_info(vmf, &ra_info);
 	if (ra_info.win == 1)