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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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a914443627
Running one program that continuously hotplugs and replugs a cpu concurrently with another program that continuously writes to the scaling_setspeed node eventually deadlocks with: ============================================= [ INFO: possible recursive locking detected ] 3.4.0 #37 Tainted: G W --------------------------------------------- filemonkey/122 is trying to acquire lock: (s_active#13){++++.+}, at: [<c01a3d28>] sysfs_remove_dir+0x9c/0xb4 but task is already holding lock: (s_active#13){++++.+}, at: [<c01a22f0>] sysfs_write_file+0xe8/0x140 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(s_active#13); lock(s_active#13); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by filemonkey/122: #0: (&buffer->mutex){+.+.+.}, at: [<c01a2230>] sysfs_write_file+0x28/0x140 #1: (s_active#13){++++.+}, at: [<c01a22f0>] sysfs_write_file+0xe8/0x140 stack backtrace: [<c0014fcc>] (unwind_backtrace+0x0/0x120) from [<c00ca600>] (validate_chain+0x6f8/0x1054) [<c00ca600>] (validate_chain+0x6f8/0x1054) from [<c00cb778>] (__lock_acquire+0x81c/0x8d8) [<c00cb778>] (__lock_acquire+0x81c/0x8d8) from [<c00cb9c0>] (lock_acquire+0x18c/0x1e8) [<c00cb9c0>] (lock_acquire+0x18c/0x1e8) from [<c01a3ba8>] (sysfs_addrm_finish+0xd0/0x180) [<c01a3ba8>] (sysfs_addrm_finish+0xd0/0x180) from [<c01a3d28>] (sysfs_remove_dir+0x9c/0xb4) [<c01a3d28>] (sysfs_remove_dir+0x9c/0xb4) from [<c02d0e5c>] (kobject_del+0x10/0x38) [<c02d0e5c>] (kobject_del+0x10/0x38) from [<c02d0f74>] (kobject_release+0xf0/0x194) [<c02d0f74>] (kobject_release+0xf0/0x194) from [<c0565a98>] (cpufreq_cpu_put+0xc/0x24) [<c0565a98>] (cpufreq_cpu_put+0xc/0x24) from [<c05683f0>] (store+0x6c/0x74) [<c05683f0>] (store+0x6c/0x74) from [<c01a2314>] (sysfs_write_file+0x10c/0x140) [<c01a2314>] (sysfs_write_file+0x10c/0x140) from [<c014af44>] (vfs_write+0xb0/0x128) [<c014af44>] (vfs_write+0xb0/0x128) from [<c014b06c>] (sys_write+0x3c/0x68) [<c014b06c>] (sys_write+0x3c/0x68) from [<c000e0e0>] (ret_fast_syscall+0x0/0x3c) This is because store() in cpufreq.c indirectly calls kobject_get() via cpufreq_cpu_get() and is the last one to call kobject_put() via cpufreq_cpu_put(). Sysfs code should not call kobject_get() or kobject_put() directly (see the comment around sysfs_schedule_callback() for more information). Fix this deadlock by introducing two new functions: struct cpufreq_policy *cpufreq_cpu_get_sysfs(unsigned int cpu) void cpufreq_cpu_put_sysfs(struct cpufreq_policy *data) which do the same thing as cpufreq_cpu_{get,put}() but don't call kobject functions. To easily trigger this deadlock you can insert an msleep() with a reasonably large value right after the fail label at the bottom of the store() function in cpufreq.c and then write scaling_setspeed in one task and offline the cpu in another. The first task will hang and be detected by the hung task detector. Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> |
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| .. | ||
| acpi-cpufreq.c | ||
| cpufreq_conservative.c | ||
| cpufreq_ondemand.c | ||
| cpufreq_performance.c | ||
| cpufreq_powersave.c | ||
| cpufreq_stats.c | ||
| cpufreq_userspace.c | ||
| cpufreq-nforce2.c | ||
| cpufreq.c | ||
| db8500-cpufreq.c | ||
| e_powersaver.c | ||
| elanfreq.c | ||
| exynos4x12-cpufreq.c | ||
| exynos4210-cpufreq.c | ||
| exynos5250-cpufreq.c | ||
| exynos-cpufreq.c | ||
| freq_table.c | ||
| gx-suspmod.c | ||
| Kconfig | ||
| Kconfig.arm | ||
| Kconfig.powerpc | ||
| Kconfig.x86 | ||
| longhaul.c | ||
| longhaul.h | ||
| longrun.c | ||
| Makefile | ||
| maple-cpufreq.c | ||
| mperf.c | ||
| mperf.h | ||
| omap-cpufreq.c | ||
| p4-clockmod.c | ||
| pcc-cpufreq.c | ||
| powernow-k6.c | ||
| powernow-k7.c | ||
| powernow-k7.h | ||
| powernow-k8.c | ||
| powernow-k8.h | ||
| s3c64xx-cpufreq.c | ||
| s3c2416-cpufreq.c | ||
| s5pv210-cpufreq.c | ||
| sc520_freq.c | ||
| speedstep-centrino.c | ||
| speedstep-ich.c | ||
| speedstep-lib.c | ||
| speedstep-lib.h | ||
| speedstep-smi.c | ||