[ Sasha's backport helper bot ]
Hi,
Summary of potential issues:
ℹ️ Patch is missing in 6.13.y (ignore if backport was sent)
⚠️ Commit missing in all newer stable branches
The upstream commit SHA1 provided is correct: b583ef82b671c9a752fbe3e95bd4c1c51eab764d
WARNING: Author mismatch between patch and upstream commit:
Backport author: Christian Simon<simon@xxxxxxxx>
Commit author: Jiri Olsa<jolsa@xxxxxxxxxx>
Status in newer kernel trees:
6.13.y | Present (exact SHA1)
6.6.y | Not found
Note: The patch differs from the upstream commit:
---
1: b583ef82b671c ! 1: b3a3f2344d131 uprobes: Fix race in uprobe_free_utask
@@
## Metadata ##
-Author: Jiri Olsa <jolsa@xxxxxxxxxx>
+Author: Christian Simon <simon@xxxxxxxx>
## Commit message ##
uprobes: Fix race in uprobe_free_utask
+ commit b583ef82b671c9a752fbe3e95bd4c1c51eab764d upstream.
+
+ Christian Simon verified the regression exists in v6.12.17 as per method
+ below and backported the mainline fix to the older version of
+ uprobe_free_utask. After that change I can no longer reproduce
+ the race with this method within 1h, while before it would show the
+ panic under a minute.
+
Max Makarov reported kernel panic [1] in perf user callchain code.
The reason for that is the race between uprobe_free_utask and bpf
@@ Commit message
Fixes: cfa7f3d2c526 ("perf,x86: avoid missing caller address in stack traces captured in uprobe")
Reported-by: Max Makarov <maxpain@xxxxxxxxx>
+ (cherry picked from commit b583ef82b671c9a752fbe3e95bd4c1c51eab764d)
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20250109141440.2692173-1-jolsa@xxxxxxxxxx
+ [Christian Simon: Rebased for 6.12.y, due to mainline change https://lore.kernel.org/all/20240929144239.GA9475@xxxxxxxxxx/]
+ Signed-off-by: Christian Simon <simon@xxxxxxxx>
## kernel/events/uprobes.c ##
@@ kernel/events/uprobes.c: void uprobe_free_utask(struct task_struct *t)
@@ kernel/events/uprobes.c: void uprobe_free_utask(struct task_struct *t)
return;
+ t->utask = NULL;
- WARN_ON_ONCE(utask->active_uprobe || utask->xol_vaddr);
+ if (utask->active_uprobe)
+ put_uprobe(utask->active_uprobe);
- timer_delete_sync(&utask->ri_timer);
@@ kernel/events/uprobes.c: void uprobe_free_utask(struct task_struct *t)
- ri = free_ret_instance(ri, true /* cleanup_hprobe */);
+ xol_free_insn_slot(t);
kfree(utask);
- t->utask = NULL;
}
- #define RI_TIMER_PERIOD (HZ / 10) /* 100 ms */
+ /*
---
Results of testing on various branches:
| Branch | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.12.y | Success | Success |
