Messages in this thread | | | Subject | Re: [PATCH v2] swap: warn when a swap area overflows the maximum size | From | Raymond Jennings <> | Date | Sun, 07 Jul 2013 13:56:45 -0700 |
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Screwed up and didn't attach my fixed test log to the second version.
See below.
On Sun, 2013-07-07 at 15:31 -0400, Rik van Riel wrote: > On 07/07/2013 03:13 PM, Raymond Jennings wrote: > > Turned the comparison around for clarity of "bigger than" > > > > No semantic changes, if it still compiles it should do the same thing so > > I've omitted the testing this time. Will be happy to retest if required > > but I'm on an atom 330 and kernel rebuilds are a nightmare. > > Added CC: Andrew Morton, since this should probably go into -mm :) > > > ---- > > > > 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> > > Reviewed-by: Rik van Riel <riel@redhat.com> > > > 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 (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 */ > > > > ---- > > > > 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
On Sun, 2013-07-07 at 04:52 -0700, Raymond Jennings wrote: > # lvresize /dev/system/swap --size 16G
Typo in the second test.
The first line should read:
# lvresize /dev/system/swap --size 64G
First ever serious patch, got excited and burned the copypasta.
> # mkswap /dev/system/swap > # swapon /dev/system/swap
> > # 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 > > > > > >
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