From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 29 Aug 2007 19:08:04 -0700 From: Andrew Morton Subject: Re: [patch][rfc] radix-tree: be a nice citizen Message-Id: <20070829190804.c4a4587d.akpm@linux-foundation.org> In-Reply-To: <20070830012237.GA19405@wotan.suse.de> References: <20070829085039.GA32236@wotan.suse.de> <20070829015702.7c8567c2.akpm@linux-foundation.org> <20070829090301.GB32236@wotan.suse.de> <20070829022044.9730888e.akpm@linux-foundation.org> <20070829094503.GC32236@wotan.suse.de> <20070829154531.fd6d67bc.akpm@linux-foundation.org> <20070830012237.GA19405@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Linux Memory Management List List-ID: On Thu, 30 Aug 2007 03:22:37 +0200 Nick Piggin wrote: > On Wed, Aug 29, 2007 at 03:45:31PM -0700, Andrew Morton wrote: > > On Wed, 29 Aug 2007 11:45:03 +0200 Nick Piggin wrote: > > > > > Yeah I'm sure the radix_tree_insert isn't failing, but the > > > first kmem_cache_alloc in radix_tree_node_alloc is failing (page > > > allocator is giving the backtrace). Because it is GFP_ATOMIC and > > > being done under the spinlock. > > > > OK, that's expected. Add a __GFP_NOWARN to the caller's gfp_t? > > It eats GFP_ATOMIC reserves Really? The caller does a great pile of GFP_HIGHUSER pagecache allocations for each page which he allocates for ratnodes. I guess if we're a highmem machine then we could be low on ZONE_NORMAL, but have plenty of ZONE_HIGHMEM available, so maybe in that situation the kernel could end up chewing away a significant amount of the lowmem reserve, dunno. But I'm more suspecting that your ZONE_NORMAL got eaten by something else (networking?) and the radix-tree allocation failure you saw was collateral damage? > (and yes, we could ad a ~__GFP_HIGH, but > the allocator still has a small reserve for non-sleeping GFP_KERNEL > allocations, so it would eat that). spose so. I'm still struggling to see whether the value of the proposed fix is worth the additional overhead? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org