From: Johannes Weiner hannes@cmpxchg.org
[ Upstream commit c3466952ca1514158d7c16c9cfc48c27d5c5dc0f ]
The psi window size is a u64 an can be up to 10 seconds right now, which exceeds the lower 32 bits of the variable. We currently use div_u64 for it, which is meant only for 32-bit divisors. The result is garbage pressure sampling values and even potential div0 crashes.
Use div64_u64.
Signed-off-by: Johannes Weiner hannes@cmpxchg.org Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Suren Baghdasaryan surenb@google.com Cc: Jingfeng Xie xiejingfeng@linux.alibaba.com Link: https://lkml.kernel.org/r/20191203183524.41378-3-hannes@cmpxchg.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/sched/psi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index 970db4686dd4..ce8f6748678a 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -482,7 +482,7 @@ static u64 window_update(struct psi_window *win, u64 now, u64 value) u32 remaining;
remaining = win->size - elapsed; - growth += div_u64(win->prev_growth * remaining, win->size); + growth += div64_u64(win->prev_growth * remaining, win->size); }
return growth;