From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <458787FF.6080404@yahoo.com.au> Date: Tue, 19 Dec 2006 17:34:39 +1100 From: Nick Piggin MIME-Version: 1.0 Subject: Re: [RFC][PATCH] Fix area->nr_free-- went (-1) issue in buddy system References: <6d6a94c50612181901m1bfd9d1bsc2d9496ab24eb3f8@mail.gmail.com> <458760B0.7090803@yahoo.com.au> <6d6a94c50612182216r15cd99a3p59bbe3d49cb482f0@mail.gmail.com> In-Reply-To: <6d6a94c50612182216r15cd99a3p59bbe3d49cb482f0@mail.gmail.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Aubrey Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Hi Aubery! Aubrey wrote: > Hi Nick, > > Thanks for your reply again, ;-). > > On 12/19/06, Nick Piggin wrote: > >> >> This should not happen because the pages are checked to ensure they are >> from the same zone before merging. > > > How? page_is_buddy() only check if the buddy has the buddy flag and > has the same order. > Where can I find the same zone is checked? Ah OK, you're using 2.6.16? Later kernels have a check for this. I guess you could backport it? > >> >> What kind of system do you have? What is the dmesg and the .config? > > > I'm using the blackfin uclinux. dmesg and .config is attached. > >> It could be that the zones are not properly aligned and >> CONFIG_HOLES_IN_ZONE >> is not set. > > > I changed the code in paging_init(), see below: > ----------------------------------------- > #if 0 > zones_size[ZONE_DMA] = (end_mem - PAGE_OFFSET) >> > PAGE_SHIFT; > zones_size[ZONE_NORMAL] = 0; > #else > zones_size[ZONE_DMA] = (end_mem/2 - PAGE_OFFSET) >> > PAGE_SHIFT; > zones_size[ZONE_NORMAL] = (end_mem/2 - PAGE_OFFSET) >> > PAGE_SHIFT; > #endif > ----------------------------------------- > This is only what I did the change. I also suspect the zones are not > properly aligned, But how to align it? I think our system doesn't need > CONFIG_HOLES_IN_ZONE. That's right. I guess you can either align your zone sizes (must be aligned to MAX_ORDER size), or add the zone check in page_is_buddy. Hope that works. Nick -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com -- 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