From b0ba2d0faf6520dd0e534a9410114e043e9ab084 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Wed, 2 Aug 2017 13:32:09 -0700 Subject: mm/page_io.c: fix oops during block io poll in swapin path When a thread is OOM-killed during swap_readpage() operation, an oops occurs because end_swap_bio_read() is calling wake_up_process() based on an assumption that the thread which called swap_readpage() is still alive. Out of memory: Kill process 525 (polkitd) score 0 or sacrifice child Killed process 525 (polkitd) total-vm:528128kB, anon-rss:0kB, file-rss:4kB, shmem-rss:0kB oom_reaper: reaped process 525 (polkitd), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC Modules linked in: nf_conntrack_netbios_ns nf_conntrack_broadcast ip6t_rpfilter ipt_REJECT nf_reject_ipv4 ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set nfnetlink ebtable_nat ebtable_broute bridge stp llc ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_raw iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_raw ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter coretemp ppdev pcspkr vmw_balloon sg shpchp vmw_vmci parport_pc parport i2c_piix4 ip_tables xfs libcrc32c sd_mod sr_mod cdrom ata_generic pata_acpi vmwgfx ahci libahci drm_kms_helper ata_piix syscopyarea sysfillrect sysimgblt fb_sys_fops mptspi scsi_transport_spi ttm e1000 mptscsih drm mptbase i2c_core libata serio_raw CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.13.0-rc2-next-20170725 #129 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013 task: ffffffffb7c16500 task.stack: ffffffffb7c00000 RIP: 0010:__lock_acquire+0x151/0x12f0 Call Trace: lock_acquire+0x59/0x80 _raw_spin_lock_irqsave+0x3b/0x4f try_to_wake_up+0x3b/0x410 wake_up_process+0x10/0x20 end_swap_bio_read+0x6f/0xf0 bio_endio+0x92/0xb0 blk_update_request+0x88/0x270 scsi_end_request+0x32/0x1c0 scsi_io_completion+0x209/0x680 scsi_finish_command+0xd4/0x120 scsi_softirq_done+0x120/0x140 __blk_mq_complete_request_remote+0xe/0x10 flush_smp_call_function_queue+0x51/0x120 generic_smp_call_function_single_interrupt+0xe/0x20 smp_trace_call_function_single_interrupt+0x22/0x30 smp_call_function_single_interrupt+0x9/0x10 call_function_single_interrupt+0xa7/0xb0 RIP: 0010:native_safe_halt+0x6/0x10 default_idle+0xe/0x20 arch_cpu_idle+0xa/0x10 default_idle_call+0x1e/0x30 do_idle+0x187/0x200 cpu_startup_entry+0x6e/0x70 rest_init+0xd0/0xe0 start_kernel+0x456/0x477 x86_64_start_reservations+0x24/0x26 x86_64_start_kernel+0xf7/0x11a secondary_startup_64+0xa5/0xa5 Code: c3 49 81 3f 20 9e 0b b8 41 bc 00 00 00 00 44 0f 45 e2 83 fe 01 0f 87 62 ff ff ff 89 f0 49 8b 44 c7 08 48 85 c0 0f 84 52 ff ff ff ff 80 98 01 00 00 8b 3d 5a 49 c4 01 45 8b b3 18 0c 00 00 85 RIP: __lock_acquire+0x151/0x12f0 RSP: ffffa01f39e03c50 ---[ end trace 6c441db499169b1e ]--- Kernel panic - not syncing: Fatal exception in interrupt Kernel Offset: 0x36000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) ---[ end Kernel panic - not syncing: Fatal exception in interrupt Fix it by holding a reference to the thread. [akpm@linux-foundation.org: add comment] Fixes: 23955622ff8d231b ("swap: add block io poll in swapin path") Signed-off-by: Tetsuo Handa Reviewed-by: Shaohua Li Cc: Tim Chen Cc: Huang Ying Cc: Jens Axboe Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_io.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/page_io.c b/mm/page_io.c index b6c4ac388209..5f61b54ee1f3 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -22,6 +22,7 @@ #include #include #include +#include #include static struct bio *get_swap_bio(gfp_t gfp_flags, @@ -136,6 +137,7 @@ out: WRITE_ONCE(bio->bi_private, NULL); bio_put(bio); wake_up_process(waiter); + put_task_struct(waiter); } int generic_swapfile_activate(struct swap_info_struct *sis, @@ -378,6 +380,11 @@ int swap_readpage(struct page *page, bool do_poll) goto out; } bdev = bio->bi_bdev; + /* + * Keep this task valid during swap readpage because the oom killer may + * attempt to access it in the page fault retry time check. + */ + get_task_struct(current); bio->bi_private = current; bio_set_op_attrs(bio, REQ_OP_READ, 0); count_vm_event(PSWPIN); -- cgit v1.2.3