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kernel_optimize_test/arch/mips/kernel
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Paul Burton b63e132b64
MIPS: Use async IPIs for arch_trigger_cpumask_backtrace() 
The current MIPS implementation of arch_trigger_cpumask_backtrace() is
broken because it attempts to use synchronous IPIs despite the fact that
it may be run with interrupts disabled.

This means that when arch_trigger_cpumask_backtrace() is invoked, for
example by the RCU CPU stall watchdog, we may:

  - Deadlock due to use of synchronous IPIs with interrupts disabled,
    causing the CPU that's attempting to generate the backtrace output
    to hang itself.

  - Not succeed in generating the desired output from remote CPUs.

  - Produce warnings about this from smp_call_function_many(), for
    example:

    [42760.526910] INFO: rcu_sched detected stalls on CPUs/tasks:
    [42760.535755]  0-...!: (1 GPs behind) idle=ade/140000000000000/0 softirq=526944/526945 fqs=0
    [42760.547874]  1-...!: (0 ticks this GP) idle=e4a/140000000000000/0 softirq=547885/547885 fqs=0
    [42760.559869]  (detected by 2, t=2162 jiffies, g=266689, c=266688, q=33)
    [42760.568927] ------------[ cut here ]------------
    [42760.576146] WARNING: CPU: 2 PID: 1216 at kernel/smp.c:416 smp_call_function_many+0x88/0x20c
    [42760.587839] Modules linked in:
    [42760.593152] CPU: 2 PID: 1216 Comm: sh Not tainted 4.15.4-00373-gee058bb4d0c2 #2
    [42760.603767] Stack : 8e09bd20 8e09bd20 8e09bd20 fffffff0 00000007 00000006 00000000 8e09bca8
    [42760.616937]         95b2b379 95b2b379 807a0080 00000007 81944518 0000018a 00000032 00000000
    [42760.630095]         00000000 00000030 80000000 00000000 806eca74 00000009 8017e2b8 000001a0
    [42760.643169]         00000000 00000002 00000000 8e09baa4 00000008 808b8008 86d69080 8e09bca0
    [42760.656282]         8e09ad50 805e20aa 00000000 00000000 00000000 8017e2b8 00000009 801070ca
    [42760.669424]         ...
    [42760.673919] Call Trace:
    [42760.678672] [<27fde568>] show_stack+0x70/0xf0
    [42760.685417] [<84751641>] dump_stack+0xaa/0xd0
    [42760.692188] [<699d671c>] __warn+0x80/0x92
    [42760.698549] [<68915d41>] warn_slowpath_null+0x28/0x36
    [42760.705912] [<f7c76c1c>] smp_call_function_many+0x88/0x20c
    [42760.713696] [<6bbdfc2a>] arch_trigger_cpumask_backtrace+0x30/0x4a
    [42760.722216] [<f845bd33>] rcu_dump_cpu_stacks+0x6a/0x98
    [42760.729580] [<796e7629>] rcu_check_callbacks+0x672/0x6ac
    [42760.737476] [<059b3b43>] update_process_times+0x18/0x34
    [42760.744981] [<6eb94941>] tick_sched_handle.isra.5+0x26/0x38
    [42760.752793] [<478d3d70>] tick_sched_timer+0x1c/0x50
    [42760.759882] [<e56ea39f>] __hrtimer_run_queues+0xc6/0x226
    [42760.767418] [<e88bbcae>] hrtimer_interrupt+0x88/0x19a
    [42760.775031] [<6765a19e>] gic_compare_interrupt+0x2e/0x3a
    [42760.782761] [<0558bf5f>] handle_percpu_devid_irq+0x78/0x168
    [42760.790795] [<90c11ba2>] generic_handle_irq+0x1e/0x2c
    [42760.798117] [<1b6d462c>] gic_handle_local_int+0x38/0x86
    [42760.805545] [<b2ada1c7>] gic_irq_dispatch+0xa/0x14
    [42760.812534] [<90c11ba2>] generic_handle_irq+0x1e/0x2c
    [42760.820086] [<c7521934>] do_IRQ+0x16/0x20
    [42760.826274] [<9aef3ce6>] plat_irq_dispatch+0x62/0x94
    [42760.833458] [<6a94b53c>] except_vec_vi_end+0x70/0x78
    [42760.840655] [<22284043>] smp_call_function_many+0x1ba/0x20c
    [42760.848501] [<54022b58>] smp_call_function+0x1e/0x2c
    [42760.855693] [<ab9fc705>] flush_tlb_mm+0x2a/0x98
    [42760.862730] [<0844cdd0>] tlb_flush_mmu+0x1c/0x44
    [42760.869628] [<cb259b74>] arch_tlb_finish_mmu+0x26/0x3e
    [42760.877021] [<1aeaaf74>] tlb_finish_mmu+0x18/0x66
    [42760.883907] [<b3fce717>] exit_mmap+0x76/0xea
    [42760.890428] [<c4c8a2f6>] mmput+0x80/0x11a
    [42760.896632] [<a41a08f4>] do_exit+0x1f4/0x80c
    [42760.903158] [<ee01cef6>] do_group_exit+0x20/0x7e
    [42760.909990] [<13fa8d54>] __wake_up_parent+0x0/0x1e
    [42760.917045] [<46cf89d0>] smp_call_function_many+0x1a2/0x20c
    [42760.924893] [<8c21a93b>] syscall_common+0x14/0x1c
    [42760.931765] ---[ end trace 02aa09da9dc52a60 ]---
    [42760.938342] ------------[ cut here ]------------
    [42760.945311] WARNING: CPU: 2 PID: 1216 at kernel/smp.c:291 smp_call_function_single+0xee/0xf8
    ...

This patch switches MIPS' arch_trigger_cpumask_backtrace() to use async
IPIs & smp_call_function_single_async() in order to resolve this
problem. We ensure use of the pre-allocated call_single_data_t
structures is serialized by maintaining a cpumask indicating that
they're busy, and refusing to attempt to send an IPI when a CPU's bit is
set in this mask. This should only happen if a CPU hasn't responded to a
previous backtrace IPI - ie. if it's hung - and we print a warning to
the console in this case.

I've marked this for stable branches as far back as v4.9, to which it
applies cleanly. Strictly speaking the faulty MIPS implementation can be
traced further back to commit 856839b768 ("MIPS: Add
arch_trigger_all_cpu_backtrace() function") in v3.19, but kernel
versions v3.19 through v4.8 will require further work to backport due to
the rework performed in commit 9a01c3ed5c ("nmi_backtrace: add more
trigger_*_cpu_backtrace() methods").

Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/19597/
Cc: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org # v4.9+
Fixes: 856839b768 ("MIPS: Add arch_trigger_all_cpu_backtrace() function")
Fixes: 9a01c3ed5c ("nmi_backtrace: add more trigger_*_cpu_backtrace() methods")
2018-06-28 14:14:41 -07:00
..
.gitignore
8250-platform.c
asm-offsets.c Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
binfmt_elfn32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
binfmt_elfo32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
bmips_5xxx_init.S
bmips_vec.S
branch.c MIPS: Use proper kernel-doc Return keyword 2018-01-18 22:29:02 +00:00
cacheinfo.c MIPS: Fix cacheinfo overflow 2017-02-13 18:57:34 +00:00
cevt-bcm1480.c MIPS: clockevent drivers: Set ->min_delta_ticks and ->max_delta_ticks 2017-04-14 13:11:16 -07:00
cevt-ds1287.c MIPS: clockevent drivers: Set ->min_delta_ticks and ->max_delta_ticks 2017-04-14 13:11:16 -07:00
cevt-gt641xx.c MIPS: clockevent drivers: Set ->min_delta_ticks and ->max_delta_ticks 2017-04-14 13:11:16 -07:00
cevt-r4k.c MIPS: cevt-r4k: Fix out-of-bounds array access 2017-04-10 13:31:12 +02:00
cevt-sb1250.c MIPS: clockevent drivers: Set ->min_delta_ticks and ->max_delta_ticks 2017-04-14 13:11:16 -07:00
cevt-txx9.c MIPS: clockevent drivers: Set ->min_delta_ticks and ->max_delta_ticks 2017-04-14 13:11:16 -07:00
cmpxchg.c Update MIPS email addresses 2017-11-03 09:02:30 -07:00
cps-vec-ns16550.S Update MIPS email addresses 2017-11-03 09:02:30 -07:00
cps-vec.S MIPS: CPS: Fix MIPS_ISA_LEVEL_RAW fallout 2018-02-05 11:53:06 +00:00
cpu-bugs64.c MIPS: Fix printk continuations in cpu-bugs64.c 2017-01-24 18:30:34 +01:00
cpu-probe.c MIPS: Probe for MIPS MT perf counters per TC 2018-05-15 13:33:48 +01:00
crash_dump.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crash.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
csrc-bcm1480.c clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
csrc-ioasic.c clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
csrc-r4k.c clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
csrc-sb1250.c clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
early_printk_8250.c
early_printk.c
elf.c Update MIPS email addresses 2017-11-03 09:02:30 -07:00
entry.S MIPS: Add syscall detection for restartable sequences 2018-06-19 21:13:56 -07:00
ftrace.c MIPS: ftrace: Remove pointer comparison to 0 in prepare_ftrace_return 2018-01-18 21:59:24 +00:00
genex.S MIPS: Add DWARF unwinding to assembly 2017-09-06 11:01:52 +02:00
gpio_txx9.c
head.S MIPS: head: Reorder instructions missing a delay slot 2017-06-27 23:35:21 +02:00
i8253.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
idle.c MIPS: Include linux/cpu.h for arch_cpu_idle() 2017-08-29 15:21:54 +02:00
irq_txx9.c
irq-gt641xx.c
irq-msc01.c
irq-rm7000.c
irq.c MIPS: Introduce irq_stack 2017-01-03 16:34:34 +01:00
jump_label.c jump_label: Reorder hotplug lock and jump_label_lock 2017-05-26 10:10:45 +02:00
kgdb.c MIPS: KGDB: Use kernel context for sleeping threads 2017-04-12 22:29:22 +02:00
kprobes.c MIPS: tracing: disable uprobe/kprobe on compact branch instructions 2016-10-06 17:37:40 +02:00
linux32.c mm: add ksys_readahead() helper; remove in-kernel calls to sys_readahead() 2018-04-02 20:16:12 +02:00
machine_kexec.c MIPS: kexec: add debug info about the new kexec'ed image 2017-01-03 16:34:46 +01:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mcount.S mips: ftrace: fix static function graph tracing 2018-06-19 15:00:12 -07:00
mips_machine.c
mips-cm.c MIPS: CM: Drop WARN_ON(vp != 0) 2018-01-10 16:47:25 +01:00
mips-cpc.c MIPS: CPC: Map registers using DT in mips_cpc_default_phys_base() 2018-02-08 14:02:01 +00:00
mips-mt-fpaff.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mips-mt.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mips-r2-to-r6-emul.c MIPS: Declare various variables & functions static 2017-08-29 15:21:55 +02:00
module.c Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2017-07-15 10:59:54 -07:00
octeon_switch.S Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
perf_event_mipsxx.c MIPS: perf: Fix perf with MT counting other threads 2018-05-15 15:53:44 +01:00
perf_event.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
pm-cps.c MIPS: pm-cps: Block system suspend when a JTAG probe is present 2018-03-09 13:53:26 +00:00
pm.c
probes-common.h MIPS: Update email address for Marcin Nowakowski 2017-11-02 10:58:43 +00:00
proc.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
process.c MIPS: Use async IPIs for arch_trigger_cpumask_backtrace() 2018-06-28 14:14:41 -07:00
prom.c mips: remove arch specific early_init_dt_alloc_memory_arch 2018-01-30 11:15:55 -06:00
ptrace.c MIPS changes for 4.18 2018-06-12 12:56:02 -07:00
ptrace32.c MIPS changes for 4.18 2018-06-12 12:56:02 -07:00
r4k_fpu.S MIPS: Fix MIPS64 FP save/restore on 32-bit kernels 2017-11-09 14:13:40 +00:00
r4k_switch.S Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
r2300_fpu.S MIPS: Move r2300 FP code from r2300_switch.S to r2300_fpu.S 2017-08-29 15:21:51 +02:00
r2300_switch.S Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
relocate_kernel.S
relocate.c Update MIPS email addresses 2017-11-03 09:02:30 -07:00
reset.c MIPS: Hang more efficiently on halt/powerdown/restart 2018-03-09 11:22:43 +00:00
rtlx-cmp.c
rtlx-mt.c
rtlx.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
scall32-o32.S MIPS: Wire up io_pgetevents syscall 2018-06-19 21:14:29 -07:00
scall64-64.S MIPS: Wire up io_pgetevents syscall 2018-06-19 21:14:29 -07:00
scall64-n32.S MIPS: Wire up io_pgetevents syscall 2018-06-19 21:14:29 -07:00
scall64-o32.S MIPS: Wire up io_pgetevents syscall 2018-06-19 21:14:29 -07:00
segment.c MIPS: Print segment physical address when EU=1 2016-07-28 11:44:30 +02:00
setup.c treewide: use PHYS_ADDR_MAX to avoid type casting ULLONG_MAX 2018-06-15 07:55:25 +09:00
signal_n32.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
signal_o32.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h> 2017-03-02 08:42:29 +01:00
signal-common.h
signal.c MIPS: Add ksig argument to rseq_{signal_deliver,handle_notify_resume} 2018-06-24 10:33:03 -07:00
signal32.c compat: Move compat_timespec/ timeval to compat_time.h 2018-04-19 13:29:54 +02:00
smp-bmips.c MIPS: BMIPS: Do not mask IPIs during suspend 2018-03-05 23:35:04 +00:00
smp-cmp.c MIPS: smp-cmp: Fix vpe_id build error 2017-11-01 23:23:00 +00:00
smp-cps.c MIPS: SMP-CPS: Remove duplicate assignment of core in play_dead 2018-02-05 14:36:06 +00:00
smp-mt.c MIPS: Use mips_gic_present() in place of gic_present 2017-09-04 13:53:14 +02:00
smp-up.c MIPS: SMP: Allow boot_secondary SMP op to return errors 2017-08-30 00:57:27 +02:00
smp.c MIPS changes for 4.15 2017-11-15 11:36:08 -08:00
spinlock_test.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
spram.c
stacktrace.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
sync-r4k.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
syscall.c mm: add ksys_mmap_pgoff() helper; remove in-kernel calls to sys_mmap_pgoff() 2018-04-02 20:16:11 +02:00
sysrq.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
time.c MIPS: Convert update_persistent_clock() to update_persistent_clock64() 2018-05-14 23:58:23 +01:00
topology.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
traps.c MIPS: Call dump_stack() from show_regs() 2018-06-28 11:48:54 -07:00
unaligned.c MIPS: Declare various variables & functions static 2017-08-29 15:21:55 +02:00
uprobes.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vdso.c MIPS: VDSO: Drop gic_get_usm_range() usage 2017-09-04 13:53:14 +02:00
vmlinux.lds.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vpe-cmp.c
vpe-mt.c
vpe.c MIPS: VPE: Fix spelling mistake: "uneeded" -> "unneeded" 2018-05-14 23:58:23 +01:00
watch.c MIPS: Watch: Avoid duplication of bits in mips_read_watch_registers 2018-01-23 15:46:01 +00:00