Re: [PATCH v2] swap: warn when a swap area overflows the maximum size

2013-07-07 Thread Raymond Jennings 
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 
> > Acked-by: Valdis Kletnieks 
> 
> Reviewed-by: Rik van Riel 
> 
> > 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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Re: [PATCH v2] swap: warn when a swap area overflows the maximum size

2013-07-07 Thread Rik van Riel 

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 
Acked-by: Valdis Kletnieks 


Reviewed-by: Rik van Riel 


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
# 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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Re: [PATCH v2] swap: warn when a swap area overflows the maximum size

2013-07-07 Thread Rik van Riel 

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 shent...@gmail.com
Acked-by: Valdis Kletnieks valdis.kletni...@vt.edu


Reviewed-by: Rik van Riel r...@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
# 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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To unsubscribe from this list: send the line unsubscribe linux-kernel in
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Re: [PATCH v2] swap: warn when a swap area overflows the maximum size

2013-07-07 Thread Raymond Jennings 
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 shent...@gmail.com
  Acked-by: Valdis Kletnieks valdis.kletni...@vt.edu
 
 Reviewed-by: Rik van Riel r...@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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Please read the FAQ at  http://www.tux.org/lkml/