Eric Lee / smarc-ti-linux-kernel

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Commit d6bbbd29b1de2da807753be8a3a992a72aef42de

Authored by Raymond Jennings
Committed by Linus Torvalds
1 parent ec9bed9d38
Exists in master and in 20 other branches dlt-processor-sdk-linux-03.00.00.04, newt-ti-linux-3.12.y, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.12.10, smarc-ti-linux-3.12.y, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.12.y, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

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>

Showing 1 changed file with 10 additions and 2 deletions Side-by-side Diff

... ... @@ -1926,6 +1926,7 @@
1926 1926 int i;
1927 1927 unsigned long maxpages;
1928 1928 unsigned long swapfilepages;
  1929 + unsigned long last_page;
1929 1930  
1930 1931 if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) {
1931 1932 printk(KERN_ERR "Unable to find swap-space signature\n");
... ... @@ -1968,8 +1969,15 @@
1968 1969 */
1969 1970 maxpages = swp_offset(pte_to_swp_entry(
1970 1971 swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
1971   - if (maxpages > swap_header->info.last_page) {
1972   - maxpages = swap_header->info.last_page + 1;
  1972 + last_page = swap_header->info.last_page;
  1973 + if (last_page > maxpages) {
  1974 + printk(KERN_WARNING
  1975 + "Truncating oversized swap area, only using %luk out of %luk\n",
  1976 + maxpages << (PAGE_SHIFT - 10),
  1977 + last_page << (PAGE_SHIFT - 10));
  1978 + }
  1979 + if (maxpages > last_page) {
  1980 + maxpages = last_page + 1;
1973 1981 /* p->max is an unsigned int: don't overflow it */
1974 1982 if ((unsigned int)maxpages == 0)
1975 1983 maxpages = UINT_MAX;