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perf: Split out mlock limit handling

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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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/r/20250812104018.541975109@infradead.org
This commit is contained in:
Thomas Gleixner
2025-08-15 13:12:58 +02:00
committed by Peter Zijlstra
parent e8c4f6ee8e
commit 81e026ca47
1 changed files with 38 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/events/core.c
+38 -37
View File
@@ -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;
}