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| author | Raymond Jennings <shentino@gmail.com> | 2013-09-11 14:20:16 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-11 15:57:00 -0700 |
| commit | d6bbbd29b1de2da807753be8a3a992a72aef42de (patch) | |
| tree | 99239085e01c45bbf54f0d42f921ce54c1e15747 /mm/swapfile.c | |
| parent | ec9bed9d385fd094b20fa0809c50741710afdc74 (diff) | |
| download | lwn-d6bbbd29b1de2da807753be8a3a992a72aef42de.tar.gz lwn-d6bbbd29b1de2da807753be8a3a992a72aef42de.zip | |
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 64G
# 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
[akpm@linux-foundation.org: fix warning]
Signed-off-by: Raymond Jennings <shentino@gmail.com>
Acked-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/swapfile.c')
| -rw-r--r-- | mm/swapfile.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c index 6cf2e60983b7..b5212eea6c3c 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1926,6 +1926,7 @@ static unsigned long read_swap_header(struct swap_info_struct *p, int i; unsigned long maxpages; unsigned long swapfilepages; + unsigned long last_page; if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { printk(KERN_ERR "Unable to find swap-space signature\n"); @@ -1968,8 +1969,15 @@ 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) { - maxpages = swap_header->info.last_page + 1; + last_page = swap_header->info.last_page; + if (last_page > maxpages) { + printk(KERN_WARNING + "Truncating oversized swap area, only using %luk out of %luk\n", + maxpages << (PAGE_SHIFT - 10), + last_page << (PAGE_SHIFT - 10)); + } + if (maxpages > last_page) { + maxpages = last_page + 1; /* p->max is an unsigned int: don't overflow it */ if ((unsigned int)maxpages == 0) maxpages = UINT_MAX; |