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=1216d478300000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=47e4697be2f5b985 >> dashboard link: https://syzkaller.appspot.com/bug?extid=e45919db2eab5e837646 >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+e45919db2eab5e837646@xxxxxxxxxxxxxxxxxxxxxxxxx > >+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): [<ffffffff814406db>] copy_process+0x1e1b/0x74c0 kernel/fork.c:2061 >> softirqs last enabled at (0): [<ffffffff8144071c>] copy_process+0x1e5c/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-syzkaller #0 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS 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 = ALLOC_WMARK_LOW; int nr_populated = 0, nr_account = 0; + LIST_HEAD(head); if (unlikely(nr_pages <= 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] = page; + list_add(&page->lru, &head); nr_populated++; } local_unlock_irqrestore(&pagesets.lock, flags); + 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; + + for (i = 0; i < nr_pages && !list_empty(&head); i++) { + /* Skip existing pages */ + if (page_array[i]) + continue; + page = list_first_entry(&head, struct page, lru); + list_del_init(&page->lru); + page_array[i] = page; + } + } __count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account); zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);
