Commit 81e026ca authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Peter Zijlstra
Browse files

perf: Split out mlock limit handling 



To prepare for splitting the buffer allocation out into separate functions
for the ring buffer and the AUX buffer, split out mlock limit handling into
a helper function, which can be called from both.

No functional change intended.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/r/20250812104018.541975109@infradead.org
parent e8c4f6ee

kernel/events/core.c

+38 −37
Original line number Diff line number Diff line
@@ -6927,17 +6927,49 @@ static int map_range(struct perf_buffer *rb, struct vm_area_struct *vma) 
	return err;

}



static bool perf_mmap_calc_limits(struct vm_area_struct *vma, long *user_extra, long *extra)

{

	unsigned long user_locked, user_lock_limit, locked, lock_limit;

	struct user_struct *user = current_user();



	user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);

	/* Increase the limit linearly with more CPUs */

	user_lock_limit *= num_online_cpus();



	user_locked = atomic_long_read(&user->locked_vm);



	/*

	 * sysctl_perf_event_mlock may have changed, so that

	 *     user->locked_vm > user_lock_limit

	 */

	if (user_locked > user_lock_limit)

		user_locked = user_lock_limit;

	user_locked += *user_extra;



	if (user_locked > user_lock_limit) {

		/*

		 * charge locked_vm until it hits user_lock_limit;

		 * charge the rest from pinned_vm

		 */

		*extra = user_locked - user_lock_limit;

		*user_extra -= *extra;

	}



	lock_limit = rlimit(RLIMIT_MEMLOCK);

	lock_limit >>= PAGE_SHIFT;

	locked = atomic64_read(&vma->vm_mm->pinned_vm) + *extra;



	return locked <= lock_limit || !perf_is_paranoid() || capable(CAP_IPC_LOCK);

}



static int perf_mmap(struct file *file, struct vm_area_struct *vma)

{

	struct perf_event *event = file->private_data;

	unsigned long user_locked, user_lock_limit;

	struct user_struct *user = current_user();

	unsigned long vma_size, nr_pages;

	long user_extra = 0, extra = 0;

	struct mutex *aux_mutex = NULL;

	struct perf_buffer *rb = NULL;

	unsigned long locked, lock_limit;

	unsigned long vma_size;

	unsigned long nr_pages;

	long user_extra = 0, extra = 0;

	int ret, flags = 0;

	mapped_f mapped;
@@ -7063,38 +7095,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) 
		}

	}



	user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);



	/*

	 * Increase the limit linearly with more CPUs:

	 */

	user_lock_limit *= num_online_cpus();



	user_locked = atomic_long_read(&user->locked_vm);



	/*

	 * sysctl_perf_event_mlock may have changed, so that

	 *     user->locked_vm > user_lock_limit

	 */

	if (user_locked > user_lock_limit)

		user_locked = user_lock_limit;

	user_locked += user_extra;



	if (user_locked > user_lock_limit) {

		/*

		 * charge locked_vm until it hits user_lock_limit;

		 * charge the rest from pinned_vm

		 */

		extra = user_locked - user_lock_limit;

		user_extra -= extra;

	}



	lock_limit = rlimit(RLIMIT_MEMLOCK);

	lock_limit >>= PAGE_SHIFT;

	locked = atomic64_read(&vma->vm_mm->pinned_vm) + extra;



	if ((locked > lock_limit) && perf_is_paranoid() &&

		!capable(CAP_IPC_LOCK)) {

	if (!perf_mmap_calc_limits(vma, &user_extra, &extra)) {

		ret = -EPERM;

		goto unlock;

	}