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Sat, 3 Jul 2021 12:13:07 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com X-SMAIL-MID: 45813349283235 From: Hillf Danton To: Dmitry Vyukov Cc: syzbot , Mel Gorman , kasan-dev , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] upstream test error: BUG: sleeping function called from invalid context in stack_depot_save Date: Sat, 3 Jul 2021 12:12:56 +0800 Message-Id: <20210703041256.212-1-hdanton@sina.com> In-Reply-To: References: <0000000000009e7f6405c60dbe3b@google.com> MIME-Version: 1.0 Authentication-Results: imf11.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf11.hostedemail.com: domain of hdanton@sina.com designates 202.108.3.17 as permitted sender) smtp.mailfrom=hdanton@sina.com X-Rspamd-Server: rspam02 X-Stat-Signature: wmjuggejdg543dzinjrr971bkca5yag3 X-Rspamd-Queue-Id: C53E8F0000AD X-HE-Tag: 1625285591-491457 Content-Transfer-Encoding: quoted-printable 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 Thu, 1 Jul 2021 13:10:37 +0200 Dmitry Vyukov wrote: >On Thu, Jul 1, 2021 at 1:00 PM syzbot wrote: >> >> Hello, >> >> syzbot found the following issue on: >> >> HEAD commit: dbe69e43 Merge tag 'net-next-5.14' of git://git.kernel= .org.. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=3D1216d47830= 0000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=3D47e4697be2= f5b985 >> dashboard link: https://syzkaller.appspot.com/bug?extid=3De45919db2eab= 5e837646 >> >> IMPORTANT: if you fix the issue, please add the following tag to the c= ommit: >> Reported-by: syzbot+e45919db2eab5e837646@syzkaller.appspotmail.com > >+kasan-dev@ for for stack_depot_save warning > >> BUG: sleeping function called from invalid context at mm/page_alloc.c:= 5179 >> in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 8436, name: syz= -fuzzer >> INFO: lockdep is turned off. >> irq event stamp: 0 >> hardirqs last enabled at (0): [<0000000000000000>] 0x0 >> hardirqs last disabled at (0): [] copy_process+0x1e1= b/0x74c0 kernel/fork.c:2061 >> softirqs last enabled at (0): [] copy_process+0x1e5= c/0x74c0 kernel/fork.c:2065 >> softirqs last disabled at (0): [<0000000000000000>] 0x0 >> CPU: 1 PID: 8436 Comm: syz-fuzzer Tainted: G W 5.13.0-s= yzkaller #0 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIO= S Google 01/01/2011 >> Call Trace: >> __dump_stack lib/dump_stack.c:79 [inline] >> dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:96 >> ___might_sleep.cold+0x1f1/0x237 kernel/sched/core.c:9153 >> prepare_alloc_pages+0x3da/0x580 mm/page_alloc.c:5179 >> __alloc_pages+0x12f/0x500 mm/page_alloc.c:5375 >> alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2272 >> stack_depot_save+0x39d/0x4e0 lib/stackdepot.c:303 >> save_stack+0x15e/0x1e0 mm/page_owner.c:120 >> __set_page_owner+0x50/0x290 mm/page_owner.c:181 >> prep_new_page mm/page_alloc.c:2445 [inline] >> __alloc_pages_bulk+0x8b9/0x1870 mm/page_alloc.c:5313 >> alloc_pages_bulk_array_node include/linux/gfp.h:557 [inline] >> vm_area_alloc_pages mm/vmalloc.c:2775 [inline] >> __vmalloc_area_node mm/vmalloc.c:2845 [inline] >> __vmalloc_node_range+0x39d/0x960 mm/vmalloc.c:2947 >> __vmalloc_node mm/vmalloc.c:2996 [inline] >> vzalloc+0x67/0x80 mm/vmalloc.c:3066 >> n_tty_open+0x16/0x170 drivers/tty/n_tty.c:1914 >> tty_ldisc_open+0x9b/0x110 drivers/tty/tty_ldisc.c:464 >> tty_ldisc_setup+0x43/0x100 drivers/tty/tty_ldisc.c:781 >> tty_init_dev.part.0+0x1f4/0x610 drivers/tty/tty_io.c:1461 >> tty_init_dev include/linux/err.h:36 [inline] >> tty_open_by_driver drivers/tty/tty_io.c:2102 [inline] >> tty_open+0xb16/0x1000 drivers/tty/tty_io.c:2150 >> chrdev_open+0x266/0x770 fs/char_dev.c:414 >> do_dentry_open+0x4c8/0x11c0 fs/open.c:826 >> do_open fs/namei.c:3361 [inline] >> path_openat+0x1c0e/0x27e0 fs/namei.c:3494 >> do_filp_open+0x190/0x3d0 fs/namei.c:3521 >> do_sys_openat2+0x16d/0x420 fs/open.c:1195 >> do_sys_open fs/open.c:1211 [inline] >> __do_sys_openat fs/open.c:1227 [inline] >> __se_sys_openat fs/open.c:1222 [inline] >> __x64_sys_openat+0x13f/0x1f0 fs/open.c:1222 >> do_syscall_x64 arch/x86/entry/common.c:50 [inline] >> do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 >> entry_SYSCALL_64_after_hwframe+0x44/0xae One of the quick fixes is move preparing new page out of the local lock (= with irq disabled) if it is difficult to add changes in saving stack. +++ x/mm/page_alloc.c @@ -5231,6 +5231,7 @@ unsigned long __alloc_pages_bulk(gfp_t g gfp_t alloc_gfp; unsigned int alloc_flags =3D ALLOC_WMARK_LOW; int nr_populated =3D 0, nr_account =3D 0; + LIST_HEAD(head); =20 if (unlikely(nr_pages <=3D 0)) return 0; @@ -5308,17 +5309,29 @@ unsigned long __alloc_pages_bulk(gfp_t g break; } nr_account++; - - prep_new_page(page, 0, gfp, 0); - if (page_list) - list_add(&page->lru, page_list); - else - page_array[nr_populated] =3D page; + list_add(&page->lru, &head); nr_populated++; } =20 local_unlock_irqrestore(&pagesets.lock, flags); =20 + list_for_each_entry(page, &head, lru) + prep_new_page(page, 0, gfp, 0); + + if (page_list) + list_splice(&head, page_list); + else { + int i;=20 + + for (i =3D 0; i < nr_pages && !list_empty(&head); i++) { + /* Skip existing pages */ + if (page_array[i]) + continue; + page =3D list_first_entry(&head, struct page, lru); + list_del_init(&page->lru); + page_array[i] =3D page; + } + } __count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account); zone_statistics(ac.preferred_zoneref->zone, zone, nr_account); =20