Messages in this thread | | | Date | Wed, 24 Jun 2009 19:55:24 +0300 | Subject | Re: upcoming kerneloops.org item: get_page_from_freelist | From | Pekka Enberg <> |
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Hi Andrew,
On Wed, 24 Jun 2009 08:07:53 -0700 Arjan van de Ven <arjan@infradead.org> wrote: >> a new item is coming up fast in the kerneloops.org stats, and it's new >> in 2.6.31-rc; >> >> http://www.kerneloops.org/searchweek.php?search=get_page_from_freelist >> >> it's this warning in mm/page_alloc.c: >> >> * __GFP_NOFAIL is not to be used in new code. >> * >> * All __GFP_NOFAIL callers should be fixed so that they >> * properly detect and handle allocation failures. >> * >> * We most definitely don't want callers attempting to >> * allocate greater than single-page units with >> * __GFP_NOFAIL. >> */ >> WARN_ON_ONCE(order > 0); >> >> >> typical backtraces look like >> >> get_page_from_freelist >> __alloc_pages_nodemask >> alloc_pages_current >> alloc_slab_page >> new_slab >> __slab_alloc >> kmem_cache_alloc_notrace >> start_this_handle >> jbd2_journal_start >> >> and >> >> get_page_from_freelist >> __alloc_pages_nodemask >> alloc_pages_current >> alloc_slab_page >> new_slab >> __slab_alloc >> kmem_cache_alloc_notrace >> start_this_handle >> journal_start >> ext3_journal_start_sb >> ext3_journal_start >> ext3_dirty_inode >> >> but there are some other ones as well at the url above. >> >> >> git blame shows that >> >> commit dab48dab37d2770824420d1e01730a107fade1aa >> Author: Andrew Morton <akpm@linux-foundation.org> >> Date: Tue Jun 16 15:32:37 2009 -0700 >> >> introduced this WARN_ON.....
On Wed, Jun 24, 2009 at 7:46 PM, Andrew Morton<akpm@linux-foundation.org> wrote: > Well yes. Using GFP_NOFAIL on a higher-order allocation is bad. This > patch is there to find, name, shame, blame and hopefully fix callers. > > A fix for cxgb3 is in the works. slub's design is a big problem. > > But we'll probably have to revert it for 2.6.31 :(
How is SLUB's design a problem here? Can't we just clear GFP_NOFAIL from the higher order allocation and thus force GFP_NOFAIL allocations to use the minimum required order?
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