tracing: Fix too large stack usage in do_one_initcall()
One of my testboxes triggered this nasty stack overflow crash during SCSI probing: [ 5.874004] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 5.875004] device: 'sda': device_add [ 5.878004] BUG: unable to handle kernel NULL pointer dereference at 00000a0c [ 5.878004] IP: [<b1008321>] print_context_stack+0x81/0x110 [ 5.878004] *pde = 00000000 [ 5.878004] Thread overran stack, or stack corrupted [ 5.878004] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [ 5.878004] last sysfs file: [ 5.878004] [ 5.878004] Pid: 1, comm: swapper Not tainted (2.6.31-rc6-tip-01272-g9919e28-dirty #5685) [ 5.878004] EIP: 0060:[<b1008321>] EFLAGS: 00010083 CPU: 0 [ 5.878004] EIP is at print_context_stack+0x81/0x110 [ 5.878004] EAX: cf8a3000 EBX: cf8a3fe4 ECX: 00000049 EDX: 00000000 [ 5.878004] ESI: b1cfce84 EDI: 00000000 EBP: cf8a3018 ESP: cf8a2ff4 [ 5.878004] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 [ 5.878004] Process swapper (pid: 1, ti=cf8a2000 task=cf8a8000 task.ti=cf8a3000) [ 5.878004] Stack: [ 5.878004] b1004867 fffff000 cf8a3ffc [ 5.878004] Call Trace: [ 5.878004] [<b1004867>] ? kernel_thread_helper+0x7/0x10 [ 5.878004] BUG: unable to handle kernel NULL pointer dereference at 00000a0c [ 5.878004] IP: [<b1008321>] print_context_stack+0x81/0x110 [ 5.878004] *pde = 00000000 [ 5.878004] Thread overran stack, or stack corrupted [ 5.878004] Oops: 0000 [#2] PREEMPT SMP DEBUG_PAGEALLOC The oops did not reveal any more details about the real stack that we have and the system got into an infinite loop of recursive pagefaults. So i booted with CONFIG_STACK_TRACER=y and the 'stacktrace' boot parameter. The box did not crash (timings/conditions probably changed a tiny bit to trigger the catastrophic crash), but the /debug/tracing/stack_trace file was rather revealing: Depth Size Location (72 entries) ----- ---- -------- 0) 3704 52 __change_page_attr+0xb8/0x290 1) 3652 24 __change_page_attr_set_clr+0x43/0x90 2) 3628 60 kernel_map_pages+0x108/0x120 3) 3568 40 prep_new_page+0x7d/0x130 4) 3528 84 get_page_from_freelist+0x106/0x420 5) 3444 116 __alloc_pages_nodemask+0xd7/0x550 6) 3328 36 allocate_slab+0xb1/0x100 7) 3292 36 new_slab+0x1c/0x160 8) 3256 36 __slab_alloc+0x133/0x2b0 9) 3220 4 kmem_cache_alloc+0x1bb/0x1d0 10) 3216 108 create_object+0x28/0x250 11) 3108 40 kmemleak_alloc+0x81/0xc0 12) 3068 24 kmem_cache_alloc+0x162/0x1d0 13) 3044 52 scsi_pool_alloc_command+0x29/0x70 14) 2992 20 scsi_host_alloc_command+0x22/0x70 15) 2972 24 __scsi_get_command+0x1b/0x90 16) 2948 28 scsi_get_command+0x35/0x90 17) 2920 24 scsi_setup_blk_pc_cmnd+0xd4/0x100 18) 2896 128 sd_prep_fn+0x332/0xa70 19) 2768 36 blk_peek_request+0xe7/0x1d0 20) 2732 56 scsi_request_fn+0x54/0x520 21) 2676 12 __generic_unplug_device+0x2b/0x40 22) 2664 24 blk_execute_rq_nowait+0x59/0x80 23) 2640 172 blk_execute_rq+0x6b/0xb0 24) 2468 32 scsi_execute+0xe0/0x140 25) 2436 64 scsi_execute_req+0x152/0x160 26) 2372 60 scsi_vpd_inquiry+0x6c/0x90 27) 2312 44 scsi_get_vpd_page+0x112/0x160 28) 2268 52 sd_revalidate_disk+0x1df/0x320 29) 2216 92 rescan_partitions+0x98/0x330 30) 2124 52 __blkdev_get+0x309/0x350 31) 2072 8 blkdev_get+0xf/0x20 32) 2064 44 register_disk+0xff/0x120 33) 2020 36 add_disk+0x6e/0xb0 34) 1984 44 sd_probe_async+0xfb/0x1d0 35) 1940 44 __async_schedule+0xf4/0x1b0 36) 1896 8 async_schedule+0x12/0x20 37) 1888 60 sd_probe+0x305/0x360 38) 1828 44 really_probe+0x63/0x170 39) 1784 36 driver_probe_device+0x5d/0x60 40) 1748 16 __device_attach+0x49/0x50 41) 1732 32 bus_for_each_drv+0x5b/0x80 42) 1700 24 device_attach+0x6b/0x70 43) 1676 16 bus_attach_device+0x47/0x60 44) 1660 76 device_add+0x33d/0x400 45) 1584 52 scsi_sysfs_add_sdev+0x6a/0x2c0 46) 1532 108 scsi_add_lun+0x44b/0x460 47) 1424 116 scsi_probe_and_add_lun+0x182/0x4e0 48) 1308 36 __scsi_add_device+0xd9/0xe0 49) 1272 44 ata_scsi_scan_host+0x10b/0x190 50) 1228 24 async_port_probe+0x96/0xd0 51) 1204 44 __async_schedule+0xf4/0x1b0 52) 1160 8 async_schedule+0x12/0x20 53) 1152 48 ata_host_register+0x171/0x1d0 54) 1104 60 ata_pci_sff_activate_host+0xf3/0x230 55) 1044 44 ata_pci_sff_init_one+0xea/0x100 56) 1000 48 amd_init_one+0xb2/0x190 57) 952 8 local_pci_probe+0x13/0x20 58) 944 32 pci_device_probe+0x68/0x90 59) 912 44 really_probe+0x63/0x170 60) 868 36 driver_probe_device+0x5d/0x60 61) 832 20 __driver_attach+0x89/0xa0 62) 812 32 bus_for_each_dev+0x5b/0x80 63) 780 12 driver_attach+0x1e/0x20 64) 768 72 bus_add_driver+0x14b/0x2d0 65) 696 36 driver_register+0x6e/0x150 66) 660 20 __pci_register_driver+0x53/0xc0 67) 640 8 amd_init+0x14/0x16 68) 632 572 do_one_initcall+0x2b/0x1d0 69) 60 12 do_basic_setup+0x56/0x6a 70) 48 20 kernel_init+0x84/0xce 71) 28 28 kernel_thread_helper+0x7/0x10 There's a lot of fat functions on that stack trace, but the largest of all is do_one_initcall(). This is due to the boot trace entry variables being on the stack. Fixing this is relatively easy, initcalls are fundamentally serialized, so we can move the local variables to file scope. Note that this large stack footprint was present for a couple of months already - what pushed my system over the edge was the addition of kmemleak to the call-chain: 6) 3328 36 allocate_slab+0xb1/0x100 7) 3292 36 new_slab+0x1c/0x160 8) 3256 36 __slab_alloc+0x133/0x2b0 9) 3220 4 kmem_cache_alloc+0x1bb/0x1d0 10) 3216 108 create_object+0x28/0x250 11) 3108 40 kmemleak_alloc+0x81/0xc0 12) 3068 24 kmem_cache_alloc+0x162/0x1d0 13) 3044 52 scsi_pool_alloc_command+0x29/0x70 This pushes the total to ~3800 bytes, only a tiny bit more was needed to corrupt the on-kernel-stack thread_info. The fix reduces the stack footprint from 572 bytes to 28 bytes. Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <srostedt@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: <stable@kernel.org> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar
Родитель
eda1e32855
Коммит
4a683bf94b
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@ -733,13 +733,14 @@ static void __init do_ctors(void)
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int initcall_debug;
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core_param(initcall_debug, initcall_debug, bool, 0644);
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static char msgbuf[64];
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static struct boot_trace_call call;
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static struct boot_trace_ret ret;
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int do_one_initcall(initcall_t fn)
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{
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int count = preempt_count();
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ktime_t calltime, delta, rettime;
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char msgbuf[64];
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struct boot_trace_call call;
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struct boot_trace_ret ret;
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if (initcall_debug) {
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call.caller = task_pid_nr(current);
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