Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758517Ab0DBFTs (ORCPT ); Fri, 2 Apr 2010 01:19:48 -0400 Received: from exprod5og109.obsmtp.com ([64.18.0.188]:45085 "EHLO exprod5og109.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757954Ab0DBFTm convert rfc822-to-8bit (ORCPT ); Fri, 2 Apr 2010 01:19:42 -0400 MIME-Version: 1.0 In-Reply-To: <20100402135955.645F.A69D9226@jp.fujitsu.com> References: <20100402135955.645F.A69D9226@jp.fujitsu.com> Date: Fri, 2 Apr 2010 13:19:40 +0800 Message-ID: Subject: Re: [Question] race condition in mm/page_alloc.c regarding page->lru? From: TAO HU To: KOSAKI Motohiro Cc: TAO HU , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Ye Yuan.Bo-A22116" , Chang Qing-A21550 , linux-arm-kernel@lists.infradead.org, Mel Gorman , arve@android.com Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6856 Lines: 172 Hi, KOSAKI Motohiro I'm glad to know your're considering patch "mm: Check if any ..." though it is not my original purpose :) cc: Arve Hj?nnev?g who is the author On Fri, Apr 2, 2010 at 1:03 PM, KOSAKI Motohiro wrote: > Cc to Mel, > >> 2 patches related to page_alloc.c were applied. >> Does anyone see a connection between the 2 patches and the panic? >> NOTE: the full patches are attached. > > I think your attached two patches are perfectly unrelated your problem. > > "mm: Add min_free_order_shift tunable." seems makes zero sense. I don't think this patch > need to be merge. > > but "mm: Check if any page in a pageblock is reserved before marking it MIGRATE_RESERVE" > treat strange hardware correctly, I think. If Mel ack this, I hope merge it. > Mel, Can we hear your opinion? > >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index a596bfd..34a29e2 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -2551,6 +2551,20 @@ static inline unsigned long >> wait_table_bits(unsigned long size) >> ?#define LONG_ALIGN(x) (((x)+(sizeof(long))-1)&~((sizeof(long))-1)) >> >> ?/* >> + * Check if a pageblock contains reserved pages >> + */ >> +static int pageblock_is_reserved(unsigned long start_pfn) >> +{ >> + ? ? unsigned long end_pfn = start_pfn + pageblock_nr_pages; >> + ? ? unsigned long pfn; >> + >> + ? ? for (pfn = start_pfn; pfn < end_pfn; pfn++) >> + ? ? ? ? ? ? if (PageReserved(pfn_to_page(pfn))) >> + ? ? ? ? ? ? ? ? ? ? return 1; >> + ? ? return 0; >> +} >> + >> +/* >> ? * Mark a number of pageblocks as MIGRATE_RESERVE. The number >> ? * of blocks reserved is based on zone->pages_min. The memory within the >> ? * reserve will tend to store contiguous free pages. Setting min_free_kbytes >> @@ -2579,7 +2593,7 @@ static void setup_zone_migrate_reserve(struct zone *zone) >> ? ? ? ? ? ? ? ? ? ? ? continue; >> >> ? ? ? ? ? ? ? /* Blocks with reserved pages will never free, skip them. */ >> - ? ? ? ? ? ? if (PageReserved(page)) >> + ? ? ? ? ? ? if (pageblock_is_reserved(pfn)) >> ? ? ? ? ? ? ? ? ? ? ? continue; >> >> ? ? ? ? ? ? ? block_migratetype = get_pageblock_migratetype(page); >> -- >> 1.5.4.3 >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 5c44ed4..a596bfd 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -119,6 +119,7 @@ static char * const zone_names[MAX_NR_ZONES] = { >> ?}; >> >> ?int min_free_kbytes = 1024; >> +int min_free_order_shift = 1; >> >> ?unsigned long __meminitdata nr_kernel_pages; >> ?unsigned long __meminitdata nr_all_pages; >> @@ -1256,7 +1257,7 @@ int zone_watermark_ok(struct zone *z, int order, >> unsigned long mark, >> ? ? ? ? ? ? ? free_pages -= z->free_area[o].nr_free << o; >> >> ? ? ? ? ? ? ? /* Require fewer higher order pages to be free */ >> - ? ? ? ? ? ? min >>= 1; >> + ? ? ? ? ? ? min >>= min_free_order_shift; >> >> ? ? ? ? ? ? ? if (free_pages <= min) >> ? ? ? ? ? ? ? ? ? ? ? return 0; >> -- >> >> >> On Thu, Apr 1, 2010 at 12:05 PM, TAO HU wrote: >> > Hi, all >> > >> > We got a panic on our ARM (OMAP) based HW. >> > Our code is based on 2.6.29 kernel (last commit for mm/page_alloc.c is >> > cc2559bccc72767cb446f79b071d96c30c26439b) >> > >> > It appears to crash while going through pcp->list in >> > buffered_rmqueue() of mm/page_alloc.c after checking vmlinux. >> > "00100100" implies LIST_POISON1 that suggests a race condition between >> > list_add() and list_del() in my personal view. >> > However we not yet figure out locking problem regarding page.lru. >> > >> > Any known issues about race condition in mm/page_alloc.c? >> > And other hints are highly appreciated. >> > >> > ?/* Find a page of the appropriate migrate type */ >> > ? ? ? ? ? ? ? ?if (cold) { >> > ? ? ? ? ? ? ? ? ? ... ... >> > ? ? ? ? ? ? ? ?} else { >> > ? ? ? ? ? ? ? ? ? ? ? ?list_for_each_entry(page, &pcp->list, lru) >> > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?if (page_private(page) == migratetype) >> > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?break; >> > ? ? ? ? ? ? ? ?} >> > >> > <1>[120898.805267] Unable to handle kernel paging request at virtual >> > address 00100100 >> > <1>[120898.805633] pgd = c1560000 >> > <1>[120898.805786] [00100100] *pgd=897b3031, *pte=00000000, *ppte=00000000 >> > <4>[120898.806457] Internal error: Oops: 17 [#1] PREEMPT >> > ... ... >> > <4>[120898.807861] CPU: 0 ? ?Not tainted ?(2.6.29-omap1 #1) >> > <4>[120898.808044] PC is at get_page_from_freelist+0x1d0/0x4b0 >> > <4>[120898.808227] LR is at get_page_from_freelist+0xc8/0x4b0 >> > <4>[120898.808563] pc : [] ? ?lr : [] ? ?psr: 800000d3 >> > <4>[120898.808563] sp : c49fbd18 ?ip : 00000000 ?fp : c49fbd74 >> > <4>[120898.809020] r10: 00000000 ?r9 : 001000e8 ?r8 : 00000002 >> > <4>[120898.809204] r7 : 001200d2 ?r6 : 60000053 ?r5 : c0507c4c ?r4 : c49fa000 >> > <4>[120898.809509] r3 : 001000e8 ?r2 : 00100100 ?r1 : c0507c6c ?r0 : 00000001 >> > <4>[120898.809844] Flags: Nzcv ?IRQs off ?FIQs off ?Mode SVC_32 ?ISA >> > ARM ?Segment kernel >> > <4>[120898.810028] Control: 10c5387d ?Table: 82160019 ?DAC: 00000017 >> > <4>[120898.948425] Backtrace: >> > <4>[120898.948760] [] (get_page_from_freelist+0x0/0x4b0) >> > from [] (__alloc_pages_internal+0xac/0x3e8) >> > <4>[120898.949554] [] (__alloc_pages_internal+0x0/0x3e8) >> > from [] (handle_mm_fault+0x16c/0xbac) >> > <4>[120898.950347] [] (handle_mm_fault+0x0/0xbac) from >> > [] (__get_user_pages+0x174/0x2b4) >> > <4>[120898.951019] [] (__get_user_pages+0x0/0x2b4) from >> > [] (get_user_pages+0x3c/0x44) >> > <4>[120898.951812] [] (get_user_pages+0x0/0x44) from >> > [] (get_arg_page+0x50/0xa4) >> > <4>[120898.952636] [] (get_arg_page+0x0/0xa4) from >> > [] (copy_strings+0x108/0x210) >> > <4>[120898.953430] ?r7:beffffe4 r6:00000ffc r5:00000000 r4:00000018 >> > <4>[120898.954223] [] (copy_strings+0x0/0x210) from >> > [] (copy_strings_kernel+0x3c/0x74) >> > <4>[120898.955047] [] (copy_strings_kernel+0x0/0x74) from >> > [] (do_execve+0x18c/0x2b0) >> > <4>[120898.955841] ?r5:0001e240 r4:0001e224 >> > <4>[120898.956329] [] (do_execve+0x0/0x2b0) from >> > [] (sys_execve+0x3c/0x5c) >> > <4>[120898.957153] [] (sys_execve+0x0/0x5c) from >> > [] (ret_fast_syscall+0x0/0x2c) >> > <4>[120898.957946] ?r7:0000000b r6:0001e270 r5:00000000 r4:0001d580 >> > <4>[120898.958740] Code: e1530008 0a000006 e2429018 e1a03009 (e5b32018) >> > >> > >> > >> > -- >> > Best Regards >> > Hu Tao >> > > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/