Re: [PATCH] perf/core: track the perf mlock gift separately

[sashiko-bot@kernel.org]

> The locked_vm field in struct user_struct was originally introduced by
> commit 789f90fcf6b0 ("perf_counter: per user mlock gift") to provide an
> mlock-like budget for perf measured against mm->pinned_vm (since 2011).
> 
> perf grants each user a 'gift' of perf_event_mlock_kb * online CPUs of
> buffer pages which is charged to user->locked_vm without any RLIMIT_MEMLOCK
> check.
> 
> Only pages beyond the gift are checked against RLIMIT_MEMLOCK, per-mm, via
> mm->pinned_vm, which makes it different from the standard mlock() check,
> which is per-mm and made against RLIMIT_MEMLOCK.
> 
> However, since this was introduced, a number of other components have
> utilised this field where a shared resource needed to be limited against
> RLIMIT_MEMLOCK.
> [ ... ]
> Fixes: 97d34aa65c29 ("mm/secretmem: properly account locked pages")
> Reported-by: Ameer Hamza <ameer.hamza@truenas.com>
> Closes: https://lore.kernel.org/20261002175651.811343-1-ameer.hamza@truenas.com
> Cc: stable@vger.kernel.org
> Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261003-perf-locked-vm-fix-v1-1-d214dcaf0d76@kernel.org?part=1