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Date: Sat, 11 Oct 2014 09:11:21 -0400 From: Sasha Levin <sasha.levin@...cle.com> To: Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net Subject: Re: [PATCH 3/3] f2fs: refactor flush_nat_entries to remove costly reorganizing ops On 09/23/2014 12:53 AM, Jaegeuk Kim wrote: > +static void __set_nat_cache_dirty(struct f2fs_nm_info *nm_i, > + struct nat_entry *ne) > +{ > + nid_t set = ne->ni.nid / NAT_ENTRY_PER_BLOCK; > + struct nat_entry_set *head; > + > + if (get_nat_flag(ne, IS_DIRTY)) > + return; > +retry: > + head = radix_tree_lookup(&nm_i->nat_set_root, set); > + if (!head) { > + head = f2fs_kmem_cache_alloc(nat_entry_set_slab, GFP_ATOMIC); This is funny, you call f2fs_kmem_cache_alloc() here with GFP_ATOMIC because of disabled preemption, but f2fs_kmem_cache_alloc() will attempt to cond_resched() in case of failed allocations: retry: entry = kmem_cache_alloc(cachep, flags); if (!entry) { cond_resched(); goto retry; } So in reality, f2fs_kmem_cache_alloc can't really work with GFP_ATOMIC, and right now there are two different locations that call it with that flag. Thanks, Sasha -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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