From cf46cf40bc3e7aa34b2292bee2a7df962d72a6db Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Tue, 3 Dec 2019 13:35:24 -0500 Subject: [PATCH] UPSTREAM: psi: Fix a division error in psi poll() 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 Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Suren Baghdasaryan Cc: Jingfeng Xie Link: https://lkml.kernel.org/r/20191203183524.41378-3-hannes@cmpxchg.org Signed-off-by: Sasha Levin (cherry picked from commit c3466952ca1514158d7c16c9cfc48c27d5c5dc0f) Signed-off-by: Suren Baghdasaryan Change-Id: I49fdfd55751d1a2cde19666624c9c5d76dc78dad --- 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 7404859821fc..fc14d46f68a1 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;