From: Raymond Jennings <shentino@gmail.com>
To: Rik van Riel <riel@redhat.com>
Cc: Valdis Kletnieks <valdis.kletnieks@vt.edu>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH] swap: warn when a swap area overflows the maximum size (resent)
Date: Sun, 07 Jul 2013 04:52:58 -0700 [thread overview]
Message-ID: <1373197978.26573.7.camel@warfang> (raw)
In-Reply-To: <1373197450.26573.5.camel@warfang>
Silly me, wrong email address
On Sun, 2013-07-07 at 04:44 -0700, Raymond Jennings wrote:
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.
Signed-off-by: Raymond Jennings <shentino@gmail.com>
Acked-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
----
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 36af6ee..5a4ce53 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1953,6 +1953,12 @@ static unsigned long read_swap_header(struct
swap_info_struct *p,
*/
maxpages = swp_offset(pte_to_swp_entry(
swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
+ if (maxpages < swap_header->info.last_page) {
+ 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 */
----
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
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next parent reply other threads:[~2013-07-07 11:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1373197450.26573.5.camel@warfang>
2013-07-07 11:52 ` Raymond Jennings [this message]
2013-07-07 11:58 ` [PATCH] swap: warn when a swap area overflows the maximum size (resent) Raymond Jennings
2013-07-07 12:01 ` Raymond Jennings
2013-07-07 19:13 ` [PATCH v2] swap: warn when a swap area overflows the maximum size Raymond Jennings
2013-07-07 19:31 ` Rik van Riel
2013-07-07 20:56 ` Raymond Jennings
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1373197978.26573.7.camel@warfang \
--to=shentino@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=riel@redhat.com \
--cc=valdis.kletnieks@vt.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).