On Thu, Aug 04, 2011 at 09:57:30AM +0200, Michal Hocko wrote:
> On Thu 04-08-11 11:09:48, Bob Liu wrote:
> > This patch also add checking whether alloc frontswap_map memory
> > failed.
> >
> > Signed-off-by: Bob Liu <lliubbo@xxxxxxxxx>
> > ---
> > mm/swapfile.c | 6 +++---
> > 1 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/swapfile.c b/mm/swapfile.c
> > index ffdd06a..8fe9e88 100644
> > --- a/mm/swapfile.c
> > +++ b/mm/swapfile.c
> > @@ -2124,9 +2124,9 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
> > }
> > /* frontswap enabled? set up bit-per-page map for frontswap */
> > if (frontswap_enabled) {
> > - frontswap_map = vmalloc(maxpages / sizeof(long));
> > - if (frontswap_map)
> > - memset(frontswap_map, 0, maxpages / sizeof(long));
> > + frontswap_map = vzalloc(maxpages / sizeof(long));
> > + if (!frontswap_map)
> > + goto bad_swap;
>
> vzalloc part looks good but shouldn't we disable frontswap rather than
> fail?
Silently dropping explicitely enabled features is not a good idea,
IMO. But from a quick look, this seems to be actually happening as
frontswap's bitmap tests check for whether there is even a bitmap
allocated and it should essentially never do anything for real if
there isn't.
How about printing a warning as to why the swapon fails and give the
admin a choice to disable it on her own?
It's outside this patch's scope, though, just as changing the
behaviour to fail swapon is.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>