* + swap-warn-when-a-swap-area-overflows-the-maximum-size.patch added to -mm tree
@ 2013-07-15 21:06 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2013-07-15 21:06 UTC (permalink / raw)
To: mm-commits, valdis.kletnieks, hughd, shentino
Subject: + swap-warn-when-a-swap-area-overflows-the-maximum-size.patch added to -mm tree
To: shentino@gmail.com,hughd@google.com,valdis.kletnieks@vt.edu
From: akpm@linux-foundation.org
Date: Mon, 15 Jul 2013 14:06:35 -0700
The patch titled
Subject: swap: warn when a swap area overflows the maximum size
has been added to the -mm tree. Its filename is
swap-warn-when-a-swap-area-overflows-the-maximum-size.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/swap-warn-when-a-swap-area-overflows-the-maximum-size.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/swap-warn-when-a-swap-area-overflows-the-maximum-size.patch
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------------------------------------------------------
From: Raymond Jennings <shentino@gmail.com>
Subject: swap: warn when a swap area overflows the maximum size
It is possible to swapon a swap area that is too big for the pte width
to handle.
Presently this failure happens silently.
Instead, emit a diagnostic to warn the user.
Testing results, root prompt commands and kernel log messages:
# lvresize /dev/system/swap --size 16G
# mkswap /dev/system/swap
# swapon /dev/system/swap
Jul 7 04:27:22 warfang kernel: Adding 16777212k swap
on /dev/mapper/system-swap. Priority:-1 extents:1 across:16777212k
# lvresize /dev/system/swap --size 16G
# mkswap /dev/system/swap
# swapon /dev/system/swap
Jul 7 04:27:22 warfang kernel: Truncating oversized swap area, only
using 33554432k out of 67108860k
Jul 7 04:27:22 warfang kernel: Adding 33554428k swap
on /dev/mapper/system-swap. Priority:-1 extents:1 across:33554428k
Signed-off-by: Raymond Jennings <shentino@gmail.com>
Acked-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/swapfile.c | 6 ++++++
1 file changed, 6 insertions(+)
diff -puN mm/swapfile.c~swap-warn-when-a-swap-area-overflows-the-maximum-size mm/swapfile.c
--- a/mm/swapfile.c~swap-warn-when-a-swap-area-overflows-the-maximum-size
+++ a/mm/swapfile.c
@@ -1953,6 +1953,12 @@ static unsigned long read_swap_header(st
*/
maxpages = swp_offset(pte_to_swp_entry(
swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
+ if (swap_header->info.last_page > maxpages) {
+ printk(KERN_WARNING
+ "Truncating oversized swap area, only using %luk out of %luk\n",
+ maxpages << (PAGE_SHIFT - 10),
+ swap_header->info.last_page << (PAGE_SHIFT - 10));
+ }
if (maxpages > swap_header->info.last_page) {
maxpages = swap_header->info.last_page + 1;
/* p->max is an unsigned int: don't overflow it */
_
Patches currently in -mm which might be from shentino@gmail.com are
swap-warn-when-a-swap-area-overflows-the-maximum-size.patch
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2013-07-15 21:06 + swap-warn-when-a-swap-area-overflows-the-maximum-size.patch added to -mm tree akpm
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