The following commit has been merged into the sched/urgent branch of tip: Commit-ID: c3466952ca1514158d7c16c9cfc48c27d5c5dc0f Gitweb: https://git.kernel.org/tip/c3466952ca1514158d7c16c9cfc48c27d5c5dc0f Author: Johannes Weiner <hannes@xxxxxxxxxxx> AuthorDate: Tue, 03 Dec 2019 13:35:24 -05:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Tue, 17 Dec 2019 13:32:48 +01:00 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 <hannes@xxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> Cc: Jingfeng Xie <xiejingfeng@xxxxxxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20191203183524.41378-3-hannes@xxxxxxxxxxx --- 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 970db46..ce8f674 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;
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