Subject: + swap-warn-when-a-swap-area-overflows-the-maximum-size.patch added to -mm tree To: shentino@xxxxxxxxx,hughd@xxxxxxxxxx,valdis.kletnieks@xxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx 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 Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Raymond Jennings <shentino@xxxxxxxxx> 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@xxxxxxxxx> Acked-by: Valdis Kletnieks <valdis.kletnieks@xxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- 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@xxxxxxxxx are swap-warn-when-a-swap-area-overflows-the-maximum-size.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html