Commit 169eae77 authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Ingo Molnar
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rseq: Eliminate useless task_work on execve 



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: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: default avatarIngo 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
parent 97577684

fs/exec.c

+2 −1
Original line number Diff line number Diff line
@@ -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 @@ static int bprm_execve(struct linux_binprm *bprm) 
		force_fatal_sig(SIGSEGV);



	sched_mm_cid_after_execve(current);

	rseq_set_notify_resume(current);

	current->in_execve = 0;



	return retval;

kernel/sched/core.c

+0 −1
Original line number Diff line number Diff line
@@ -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)