I was updating kmallocwd in preparation for testing "[RFC 0/3] OOM detection rework v2" patchset. I noticed an unexpected result with linux.git as of 3ad5d7e06a96 . The problem is that an OOM victim arrives at do_exit() with TIF_MEMDIE flag set but without pending SIGKILL. Is this correct behavior? ---------- diff --git a/kernel/exit.c b/kernel/exit.c index 07110c6..ea5bcd0 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -656,6 +656,7 @@ void do_exit(long code) int group_dead; TASKS_RCU(int tasks_rcu_i); + BUG_ON(test_thread_flag(TIF_MEMDIE) && !fatal_signal_pending(current)); profile_task_exit(tsk); WARN_ON(blk_needs_flush_plug(tsk)); ---------- [ 103.796002] ------------[ cut here ]------------ [ 103.797700] kernel BUG at kernel/exit.c:659! [ 103.799314] invalid opcode: 0000 [#1] SMP [ 103.800932] Modules linked in: ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 ipt_REJECT nf_reject_ipv4 nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ebtable_nat ebtable_broute bridge stp llc e\ btable_filter ebtables ip6table_mangle ip6table_security ip6table_raw ip6table_filter ip6_tables iptable_mangle iptable_security iptable_raw iptable_filter ip_tables coretemp crct10dif_pclmul crc32_pclmul crc32c_intel aesni_intel glue_h\ elper lrw gf128mul ablk_helper ppdev cryptd vmw_balloon serio_raw pcspkr parport_pc vmw_vmci parport shpchp i2c_piix4 sd_mod ata_generic pata_acpi vmwgfx drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm ahci ata_piix\ mptspi scsi_transport_spi mptscsih libahci libata mptbase e1000 i2c_core [ 103.820275] CPU: 1 PID: 11036 Comm: oom-tester4 Not tainted 4.4.0-rc1+ #9 [ 103.822514] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013 [ 103.825459] task: ffff880078f0c200 ti: ffff880078db8000 task.ti: ffff880078db8000 [ 103.827850] RIP: 0010:[<ffffffff810726ef>] [<ffffffff810726ef>] do_exit+0xa3f/0xb40 [ 103.830535] RSP: 0018:ffff880078dbbcd0 EFLAGS: 00010246 [ 103.832606] RAX: 0000000000100084 RBX: 0000000000000002 RCX: 0000000000000000 [ 103.834935] RDX: 00000000418004fc RSI: 0000000000000001 RDI: 0000000000000002 [ 103.837314] RBP: ffff880078dbbd30 R08: 0000000000000000 R09: 0000000000000000 [ 103.839595] R10: 0000000000000001 R11: ffff880078f0c930 R12: 0000000000000002 [ 103.841894] R13: ffff880078f0c200 R14: ffff880078f0c200 R15: 0000000000000008 [ 103.844305] FS: 00007fbf5610a740(0000) GS:ffff88007fc40000(0000) knlGS:0000000000000000 [ 103.846845] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 103.849002] CR2: 000055a5c65d17d0 CR3: 0000000078dfd000 CR4: 00000000001406e0 [ 103.851433] Stack: [ 103.852787] 0000000000000001 ffff880078f0c200 0000000000000046 ffff880078dbbe18 [ 103.855263] ffff880078dbbe38 ffff880078f0c200 000000005c6d8319 ffff880035dc2f40 [ 103.857717] 0000000000000002 ffff880078f0c200 ffff880078dbbe38 0000000000000008 [ 103.860138] Call Trace: [ 103.861603] [<ffffffff81072877>] do_group_exit+0x47/0xc0 include/linux/sched.h:807 kernel/exit.c:862 [ 103.863513] [<ffffffff8107e0b2>] get_signal+0x222/0x7e0 kernel/signal.c:2307 [ 103.865395] [<ffffffff8100f362>] do_signal+0x32/0x670 arch/x86/kernel/signal.c:709 [ 103.867219] [<ffffffff8106a517>] ? syscall_slow_exit_work+0x4b/0x10d arch/x86/entry/common.c:306 [ 103.869264] [<ffffffff8106a46a>] ? exit_to_usermode_loop+0x2e/0x90 arch/x86/include/asm/paravirt.h:816 arch/x86/entry/common.c:237 [ 103.871249] [<ffffffff8106a488>] exit_to_usermode_loop+0x4c/0x90 arch/x86/entry/common.c:249 [ 103.873324] [<ffffffff8100355b>] syscall_return_slowpath+0xbb/0x130 arch/x86/entry/common.c:282 arch/x86/entry/common.c:344 [ 103.875322] [<ffffffff816e85da>] int_ret_from_sys_call+0x25/0x9f arch/x86/entry/entry_64.S:282 [ 103.877228] Code: ba 9f 81 31 c0 e8 ed 6c 0c 00 48 8b b8 90 00 00 00 e8 e6 6b 02 00 e9 31 fb ff ff 49 8b 46 08 48 8b 40 08 a8 04 0f 85 bd 00 00 00 <0f> 0b 4c 89 f7 e8 77 80 0a 00 e9 fb f6 ff ff 49 8b 96 c0 05 00 [ 103.884329] RIP [<ffffffff810726ef>] do_exit+0xa3f/0xb40 kernel/exit.c:659 [ 103.886121] RSP <ffff880078dbbcd0> [ 103.887537] ---[ end trace a5e757a180b4cf32 ]--- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>