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[115.124.30.56]) by mx.google.com with ESMTPS id s11si459175pgp.326.2019.07.19.09.17.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Jul 2019 09:17:42 -0700 (PDT) Received-SPF: pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.56 as permitted sender) client-ip=115.124.30.56; Authentication-Results: mx.google.com; spf=pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.56 as permitted sender) smtp.mailfrom=yang.shi@linux.alibaba.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=alibaba.com X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R511e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04407;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0TXIWw-t_1563553057; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TXIWw-t_1563553057) by smtp.aliyun-inc.com(127.0.0.1); Sat, 20 Jul 2019 00:17:39 +0800 Subject: Re: [v3 PATCH 2/2] mm: mempolicy: handle vma with unmovable pages mapped correctly in mbind To: Vlastimil Babka , mhocko@kernel.org, mgorman@techsingularity.net, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org References: <1563470274-52126-1-git-send-email-yang.shi@linux.alibaba.com> <1563470274-52126-3-git-send-email-yang.shi@linux.alibaba.com> <6ba72e56-9f62-36bf-ded7-f337522715d5@suse.cz> From: Yang Shi Message-ID: <2a753062-a6bd-d767-085a-0bf9847ea067@linux.alibaba.com> Date: Fri, 19 Jul 2019 09:17:35 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <6ba72e56-9f62-36bf-ded7-f337522715d5@suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 7/19/19 6:01 AM, Vlastimil Babka wrote: > On 7/18/19 7:17 PM, Yang Shi wrote: >> When running syzkaller internally, we ran into the below bug on 4.9.x >> kernel: >> >> kernel BUG at mm/huge_memory.c:2124! >> invalid opcode: 0000 [#1] SMP KASAN >> Dumping ftrace buffer: >> (ftrace buffer empty) >> Modules linked in: >> CPU: 0 PID: 1518 Comm: syz-executor107 Not tainted 4.9.168+ #2 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.5.1 01/01/2011 >> task: ffff880067b34900 task.stack: ffff880068998000 >> RIP: 0010:[] [] split_huge_page_to_list+0x8fb/0x1030 mm/huge_memory.c:2124 >> RSP: 0018:ffff88006899f980 EFLAGS: 00010286 >> RAX: 0000000000000000 RBX: ffffea00018f1700 RCX: 0000000000000000 >> RDX: 1ffffd400031e2e7 RSI: 0000000000000001 RDI: ffffea00018f1738 >> RBP: ffff88006899f9e8 R08: 0000000000000001 R09: 0000000000000000 >> R10: 0000000000000000 R11: fffffbfff0d8b13e R12: ffffea00018f1400 >> R13: ffffea00018f1400 R14: ffffea00018f1720 R15: ffffea00018f1401 >> FS: 00007fa333996740(0000) GS:ffff88006c600000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 0000000020000040 CR3: 0000000066b9c000 CR4: 00000000000606f0 >> Stack: >> 0000000000000246 ffff880067b34900 0000000000000000 ffff88007ffdc000 >> 0000000000000000 ffff88006899f9e8 ffffffff812b4015 ffff880064c64e18 >> ffffea00018f1401 dffffc0000000000 ffffea00018f1700 0000000020ffd000 >> Call Trace: >> [] split_huge_page include/linux/huge_mm.h:100 [inline] >> [] queue_pages_pte_range+0x7e1/0x1480 mm/mempolicy.c:538 >> [] walk_pmd_range mm/pagewalk.c:50 [inline] >> [] walk_pud_range mm/pagewalk.c:90 [inline] >> [] walk_pgd_range mm/pagewalk.c:116 [inline] >> [] __walk_page_range+0x44a/0xdb0 mm/pagewalk.c:208 >> [] walk_page_range+0x154/0x370 mm/pagewalk.c:285 >> [] queue_pages_range+0x115/0x150 mm/mempolicy.c:694 >> [] do_mbind mm/mempolicy.c:1241 [inline] >> [] SYSC_mbind+0x3c3/0x1030 mm/mempolicy.c:1370 >> [] SyS_mbind+0x46/0x60 mm/mempolicy.c:1352 >> [] do_syscall_64+0x1d2/0x600 arch/x86/entry/common.c:282 >> [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb >> Code: c7 80 1c 02 00 e8 26 0a 76 01 <0f> 0b 48 c7 c7 40 46 45 84 e8 4c >> RIP [] split_huge_page_to_list+0x8fb/0x1030 mm/huge_memory.c:2124 >> RSP > ... > >> @@ -532,7 +531,14 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr, >> has_unmovable |= true; >> break; >> } >> - migrate_page_add(page, qp->pagelist, flags); >> + >> + /* >> + * Do not abort immediately since there may be >> + * temporary off LRU pages in the range. Still >> + * need migrate other LRU pages. >> + */ >> + if (migrate_page_add(page, qp->pagelist, flags)) >> + has_unmovable |= true; > Also = instead of |= OK > >> } else >> break; >> } >> @@ -961,10 +967,21 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask, >> /* >> * page migration, thp tail pages can be passed. >> */ >> -static void migrate_page_add(struct page *page, struct list_head *pagelist, >> +static int migrate_page_add(struct page *page, struct list_head *pagelist, >> unsigned long flags) >> { >> struct page *head = compound_head(page); >> + >> + /* >> + * Non-movable page may reach here. And, there may be >> + * temporary off LRU pages or non-LRU movable pages. >> + * Treat them as unmovable pages since they can't be >> + * isolated, so they can't be moved at the moment. It >> + * should return -EIO for this case too. >> + */ >> + if (!PageLRU(head) && (flags & MPOL_MF_STRICT)) >> + return -EIO; > As this test is racy, why not just use the result of isolate_lru_page(). Sounds good to me. Will fix in v4. Thanks, Yang > >> + >> /* >> * Avoid migrating a page that is shared with others. >> */ >> @@ -976,6 +993,8 @@ static void migrate_page_add(struct page *page, struct list_head *pagelist, >> hpage_nr_pages(head)); >> } >> } >> + >> + return 0; >> } >> >> /* page allocation callback for NUMA node migration */ >> @@ -1178,9 +1197,10 @@ static struct page *new_page(struct page *page, unsigned long start) >> } >> #else >> >> -static void migrate_page_add(struct page *page, struct list_head *pagelist, >> +static int migrate_page_add(struct page *page, struct list_head *pagelist, >> unsigned long flags) >> { >> + return -EIO; >> } >> >> int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from, >>