linux-kernel - [RFC V2] mm:add zero_page _mapcount when mapped into user space

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 2 Dec 2014 17:27:36 +0800
From:	"Wang, Yalin" <Yalin.Wang@...ymobile.com>
To:	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
	"'linux-mm@...ck.org'" <linux-mm@...ck.org>,
	"'linux-arm-kernel@...ts.infradead.org'" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: [RFC V2] mm:add zero_page _mapcount when mapped into user space

This patch add/dec zero_page's _mapcount to make sure
the mapcount is correct for zero_page,
so that when read from /proc/kpagecount, zero_page's
mapcount is also correct, userspace process like procrank can
calculate PSS correctly.

Signed-off-by: Yalin Wang <yalin.wang@...ymobile.com>
---
 mm/memory.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index 3e50383..7215423 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2198,6 +2198,7 @@ gotten:
 		new_page = alloc_zeroed_user_highpage_movable(vma, address);
 		if (!new_page)
 			goto oom;
+		atomic_dec(&pfn_to_page(pte_pfn(orig_pte))->_mapcount);
 	} else {
 		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
 		if (!new_page)
@@ -2647,6 +2648,7 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
 		if (!pte_none(*page_table))
 			goto unlock;
+		atomic_inc(&pfn_to_page(my_zero_pfn(address))->_mapcount);
 		goto setpte;
 	}
 
-- 
2.1.3
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/