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| author | David Ahern <david.ahern@oracle.com> | 2015-06-15 20:15:43 (GMT) |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-06-25 13:01:02 (GMT) |
| commit | c17af4dd96aa99e6e58b5d715a7c66db63a15106 (patch) | |
| tree | 95301a9cc6875a3425d258808a812dc2d9e7b7a7 /arch/sparc/kernel | |
| parent | aefbef10e3ae6e2c6e3c54f906f10b34c73a2c66 (diff) | |
| download | linux-c17af4dd96aa99e6e58b5d715a7c66db63a15106.tar.xz | |
sparc: perf: Disable pagefaults while walking userspace stacks
Page faults generated walking userspace stacks can call schedule to switch
out the task. When collecting callchains for scheduler tracepoints this
causes a deadlock as the tracepoints can be hit with the runqueue lock held:
[ 8138.159054] WARNING: CPU: 758 PID: 12488 at /opt/dahern/linux.git/arch/sparc/kernel/nmi.c:80 perfctr_irq+0x1f8/0x2b4()
[ 8138.203152] Watchdog detected hard LOCKUP on cpu 758
[ 8138.410969] CPU: 758 PID: 12488 Comm: perf Not tainted 4.0.0-rc6+ #6
[ 8138.437146] Call Trace:
[ 8138.447193] [000000000045cdd4] warn_slowpath_common+0x7c/0xa0
[ 8138.471238] [000000000045ce90] warn_slowpath_fmt+0x30/0x40
[ 8138.494189] [0000000000983e38] perfctr_irq+0x1f8/0x2b4
[ 8138.515716] [00000000004209f4] tl0_irq15+0x14/0x20
[ 8138.535791] [00000000009839ec] _raw_spin_trylock_bh+0x68/0x108
[ 8138.560180] [0000000000980018] __schedule+0xcc/0x710
[ 8138.580981] [00000000009806dc] preempt_schedule_common+0x10/0x3c
[ 8138.606082] [000000000098077c] _cond_resched+0x34/0x44
[ 8138.627603] [0000000000565990] kmem_cache_alloc_node+0x24/0x1a0
[ 8138.652345] [0000000000450b60] tsb_grow+0xac/0x488
[ 8138.672429] [0000000000985040] do_sparc64_fault+0x4dc/0x6e4
[ 8138.695736] [0000000000407c2c] sparc64_realfault_common+0x10/0x20
[ 8138.721202] [00000000006f2e24] NG4copy_from_user+0xa4/0x3c0
[ 8138.744510] [000000000044f900] perf_callchain_user+0x5c/0x6c
[ 8138.768182] [0000000000517b5c] perf_callchain+0x16c/0x19c
[ 8138.790774] [0000000000515f84] perf_prepare_sample+0x68/0x218
[ 8138.814801] ---[ end trace 42ca6294b1ff7573 ]---
As with PowerPC (b59a1bfcc240, "powerpc/perf: Disable pagefaults during
callchain stack read") disable pagefaults while walking userspace stacks.
Signed-off-by: David Ahern <david.ahern@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc/kernel')
| -rw-r--r-- | arch/sparc/kernel/perf_event.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c index 59cf917..48387be 100644 --- a/arch/sparc/kernel/perf_event.c +++ b/arch/sparc/kernel/perf_event.c @@ -21,7 +21,7 @@ #include <asm/stacktrace.h> #include <asm/cpudata.h> -#include <asm/uaccess.h> +#include <linux/uaccess.h> #include <linux/atomic.h> #include <asm/nmi.h> #include <asm/pcr.h> @@ -1803,8 +1803,13 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) return; flushw_user(); + + pagefault_disable(); + if (test_thread_flag(TIF_32BIT)) perf_callchain_user_32(entry, regs); else perf_callchain_user_64(entry, regs); + + pagefault_enable(); } |