On Sat, 13 Jan 2024 at 10:23, Marco Elver <elver@xxxxxxxxxx> wrote: > > On Sat, 13 Jan 2024 at 10:19, Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote: > > > > On Sat, Jan 13, 2024 at 10:12:21AM +0100, Marco Elver wrote: > > > On Sat, 13 Jan 2024 at 02:24, Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote: > > > > > > > > On Fri, Jan 12, 2024 at 11:15:05PM +0100, Marco Elver wrote: > > > > > + /* > > > > > + * Stack traces of size 0 are never saved, and we can simply use > > > > > + * the size field as an indicator if this is a new unused stack > > > > > + * record in the freelist. > > > > > + */ > > > > > + stack->size = 0; > > > > > > > > I would use WRITE_ONCE here too, at least for TSan. > > > > > > This is written with the pool_lock held. > > > > ...which doesn't help because the readers don't take it? > > This function is only refilling the freelist. Readers don't see it yet > because it's in none of the hash table buckets. The freelist is only > ever accessed under the lock. > > Once an entry is allocated from the freelist, its size is overwritten > with something non-zero (since it then contains a stack trace). Those > updates are released into the right hash table bucket with > list_add_rcu() (which implies a release). > > Am I missing something else? FWIW, the current version (draft) of this can be found here: https://git.kernel.org/pub/scm/linux/kernel/git/melver/linux.git/log/?h=kasan/dev I'll send the 2 patches next week - they should apply cleanly on current mainline. Thanks, -- Marco
