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rseq: Eliminate useless task_work on execve

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Eliminate a useless task_work on execve by moving the call to
rseq_set_notify_resume() from sched_mm_cid_after_execve() to the error
path of bprm_execve().

The call to rseq_set_notify_resume() from sched_mm_cid_after_execve() is
pointless in the success case, because rseq_execve() will clear the rseq
pointer before returning to userspace.

sched_mm_cid_after_execve() is called from both the success and error
paths of bprm_execve(). The call to rseq_set_notify_resume() is needed
on error because the mm_cid may have changed.

Also move the rseq_execve() to right after sched_mm_cid_after_execve()
in bprm_execve().

[ mingo: Merged to a recent upstream kernel, extended the changelog. ]

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250327132945.1558783-1-mathieu.desnoyers@efficios.com
This commit is contained in:
Mathieu Desnoyers 2025-03-27 09:29:45 -04:00 committed by Ingo Molnar
parent 975776841e
commit 169eae7711
2 changed files with 2 additions and 2 deletions
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3
fs/exec.c
View File

@ -1864,9 +1864,9 @@ static int bprm_execve(struct linux_binprm *bprm)
goto out;
sched_mm_cid_after_execve(current);
rseq_execve(current);
/* execve succeeded */
current->in_execve = 0;
rseq_execve(current);
user_events_execve(current);
acct_update_integrals(current);
task_numa_free(current, false);
@ -1883,6 +1883,7 @@ out:
force_fatal_sig(SIGSEGV);
sched_mm_cid_after_execve(current);
rseq_set_notify_resume(current);
current->in_execve = 0;
return retval;

1
kernel/sched/core.c
View File

@ -10703,7 +10703,6 @@ void sched_mm_cid_after_execve(struct task_struct *t)
smp_mb();
t->last_mm_cid = t->mm_cid = mm_cid_get(rq, t, mm);
}
rseq_set_notify_resume(t);
}
void sched_mm_cid_fork(struct task_struct *t)