Messages in this thread | | | Subject | Re: [GIT PULL v2] Early SLAB fixes for 2.6.31 | From | Pekka Enberg <> | Date | Thu, 18 Jun 2009 09:01:03 +0300 |
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Hi Ben,
On Thu, 2009-06-18 at 13:24 +1000, Benjamin Herrenschmidt wrote: > On Thu, 2009-06-18 at 12:00 +1000, Benjamin Herrenschmidt wrote: > > > So I'm very much ok with the whole "use magic gfp_mask to indicate what > > > works at what stage". And yes, I think it makes sense to extend it to the > > > page allocator and might_sleep too, because GFP_KERNEL has all the same > > > issues regardless of whether it's about page allocation or about slab > > > allocators. And any "might_sleep" suppression really does tend to be about > > > the exact same thing. > > > > Argh... still broken. > > > > In fact, my initial patch added it to the page allocator, which worked > > for me. Pekka patch removed that and made it slab-only. So I'm blowing > > up at boot in lockdep or so because I'm allocating page tables on > > ppc32 with __get_free_pages() and GFP_KERNEL. > > > > I'll cook up a patch. > > Here it is: > > mm: Extend gfp masking to the page allocator > > The page allocator also needs the masking of gfp flags during boot, > so this moves it out of slab/slub and uses it with the page allocator > as well. > > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> > --- > > This will also make it easier to use it for limiting allocations that > can block during suspend/resume, though doing this really fool-proof > will require some kind of synchronization in set_gfp_allowed_mask() > vs. allocations that have already started sleeping waiting for IOs. > > Index: linux-work/include/linux/gfp.h > =================================================================== > --- linux-work.orig/include/linux/gfp.h 2009-06-18 12:03:14.000000000 +1000 > +++ linux-work/include/linux/gfp.h 2009-06-18 12:08:21.000000000 +1000 > @@ -99,7 +99,7 @@ struct vm_area_struct; > __GFP_NORETRY|__GFP_NOMEMALLOC) > > /* Control slab gfp mask during early boot */ > -#define SLAB_GFP_BOOT_MASK __GFP_BITS_MASK & ~(__GFP_WAIT|__GFP_IO|__GFP_FS) > +#define GFP_BOOT_MASK __GFP_BITS_MASK & ~(__GFP_WAIT|__GFP_IO|__GFP_FS) > > /* Control allocation constraints */ > #define GFP_CONSTRAINT_MASK (__GFP_HARDWALL|__GFP_THISNODE) > @@ -348,4 +348,11 @@ static inline void oom_killer_enable(voi > oom_killer_disabled = false; > } > > +extern gfp_t gfp_allowed_mask; > + > +static inline void set_gfp_allowed_mask(gfp_t mask) > +{ > + gfp_allowed_mask = mask; > +}
The only thing I don't like about this patch is that the caller gets to decide which bits should be masked. I really think this should be a mm_late_init() function that sets the mask _internally_ in the page allocator.
But anyway, I am about to go completely off-line until Sunday or so consider the approach:
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Pekka
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