linux-kernel - [PATCH] mm: fix KPF

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Message-ID: <alpine.LSU.2.11.1702071105360.11828@eggly.anvils>
Date:   Tue, 7 Feb 2017 11:11:16 -0800 (PST)
From:   Hugh Dickins <hughd@...gle.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Wu Fengguang <fengguang.wu@...el.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH] mm: fix KPF_SWAPCACHE

4.10-rc1 commit 6326fec1122c ("mm: Use owner_priv bit for PageSwapCache,
valid when PageSwapBacked") aliased PG_swapcache to PG_owner_priv_1:
so /proc/kpageflags' KPF_SWAPCACHE should now be synthesized, instead
of being shown on unrelated pages which have PG_owner_priv_1 set.

Signed-off-by: Hugh Dickins <hughd@...gle.com>
---

 fs/proc/page.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- 4.10-rc7/fs/proc/page.c	2016-12-25 18:40:50.618454962 -0800
+++ linux/fs/proc/page.c	2017-02-07 10:28:51.019640392 -0800
@@ -173,7 +173,8 @@ u64 stable_page_flags(struct page *page)
 	u |= kpf_copy_bit(k, KPF_ACTIVE,	PG_active);
 	u |= kpf_copy_bit(k, KPF_RECLAIM,	PG_reclaim);
 
-	u |= kpf_copy_bit(k, KPF_SWAPCACHE,	PG_swapcache);
+	if (PageSwapCache(page))
+		u |= 1 << KPF_SWAPCACHE;
 	u |= kpf_copy_bit(k, KPF_SWAPBACKED,	PG_swapbacked);
 
 	u |= kpf_copy_bit(k, KPF_UNEVICTABLE,	PG_unevictable);