Messages in this thread Patch in this message | | | From | Johannes Weiner <> | Subject | [PATCH 2/2] psi: fix a division error in psi poll() | Date | Tue, 3 Dec 2019 13:35:24 -0500 |
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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> Reviewed-by: Suren Baghdasaryan <surenb@google.com> --- 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; -- 2.24.0
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