On 08/11/2016 04:42 PM, Alexander Potapenko wrote: > On Thu, Aug 11, 2016 at 12:50 AM, Andrew Morton > <[email protected]> wrote: >> On Tue, 2 Aug 2016 12:27:00 +0200 Alexander Potapenko <[email protected]> >> wrote: >> >>> If the total amount of memory assigned to quarantine is less than the >>> amount of memory assigned to per-cpu quarantines, |new_quarantine_size| >>> may overflow. Instead, set it to zero. >>> >>> ... >>> >>> --- a/mm/kasan/quarantine.c >>> +++ b/mm/kasan/quarantine.c >>> @@ -196,7 +196,7 @@ void quarantine_put(struct kasan_free_meta *info, >>> struct kmem_cache *cache) >>> >>> void quarantine_reduce(void) >>> { >>> - size_t new_quarantine_size; >>> + size_t new_quarantine_size, percpu_quarantines; >>> unsigned long flags; >>> struct qlist_head to_free = QLIST_INIT; >>> size_t size_to_free = 0; >>> @@ -214,7 +214,9 @@ void quarantine_reduce(void) >>> */ >>> new_quarantine_size = (READ_ONCE(totalram_pages) << PAGE_SHIFT) / >>> QUARANTINE_FRACTION; >>> - new_quarantine_size -= QUARANTINE_PERCPU_SIZE * num_online_cpus(); >>> + percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus(); >>> + new_quarantine_size = (new_quarantine_size < percpu_quarantines) ? >>> + 0 : new_quarantine_size - percpu_quarantines; >>> WRITE_ONCE(quarantine_size, new_quarantine_size); >>> >>> last = global_quarantine.head; >> >> Confused. Which kernel version is this supposed to apply to? > This is the second version of the patch which should've been applied > to the mainline instead of v1. > But since v1 has already hit upstream, this patch makes sense no more. > If WARN_ONCE (which is currently present in this code) is a big deal, > I can send a new patch that removes it. >
Probably not a big deal, but please, send the patch anyway.
