Hi,
On 5/19/20 2:52 PM, tip-bot2 for Thomas Gleixner wrote:
> The following commit has been merged into the core/rcu branch of tip:
>
> Commit-ID: ff5c4f5cad33061b07c3fb9187506783c0f3cb66
> Gitweb: https://git.kernel.org/tip/ff5c4f5cad33061b07c3fb9187506783c0f3cb66
> Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> AuthorDate: Fri, 13 Mar 2020 17:32:17 +01:00
> Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> CommitterDate: Tue, 19 May 2020 15:51:20 +02:00
>
> rcu/tree: Mark the idle relevant functions noinstr
>
> These functions are invoked from context tracking and other places in the
> low level entry code. Move them into the .noinstr.text section to exclude
> them from instrumentation.
>
> Mark the places which are safe to invoke traceable functions with
> instrumentation_begin/end() so objtool won't complain.
>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Reviewed-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>
> Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Link: https://lkml.kernel.org/r/20200505134100.575356107@xxxxxxxxxxxxx
>
>
> ---
I bisected a system hang condition down to this commit.
To reproduce the hang, compile the below code and execute it as root
on an x86_64 server (AMD or Intel). The code is opening a
PERF_TYPE_TRACEPOINT event with a non-zero pe.config.
If I revert the commit from Linus' ToT, the system stays up.
.config attached.
Thanks,
Kim
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <linux/perf_event.h>
#include <asm/unistd.h>
static long
perf_event_open(struct perf_event_attr *hw_event, pid_t pid,
int cpu, int group_fd, unsigned long flags)
{
int ret;
ret = syscall(__NR_perf_event_open, hw_event, pid, cpu,
group_fd, flags);
return ret;
}
int
main(int argc, char **argv)
{
struct perf_event_attr pe;
long long count;
int fd;
memset(&pe, 0, sizeof(struct perf_event_attr));
pe.type = PERF_TYPE_TRACEPOINT;
pe.size = sizeof(struct perf_event_attr);
pe.config = PERF_COUNT_HW_INSTRUCTIONS;
pe.disabled = 1;
pe.exclude_kernel = 1;
pe.exclude_hv = 1;
fd = perf_event_open(&pe, 0, -1, -1, 0);
if (fd == -1) {
fprintf(stderr, "Error opening leader %llx\n", pe.config);
exit(EXIT_FAILURE);
}
}
Attachment:
config.xz
Description: application/xz
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