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| author | Johannes Weiner <hannes@cmpxchg.org> | 2019-12-03 13:35:24 -0500 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2019-12-17 13:32:48 +0100 |
| commit | c3466952ca1514158d7c16c9cfc48c27d5c5dc0f (patch) | |
| tree | 2c5ed57633fc8461c1ba1c938e271c1f137bd8ae /kernel | |
| parent | 3dfbe25c27eab7c90c8a7e97b4c354a9d24dd985 (diff) | |
| download | linux-c3466952ca1514158d7c16c9cfc48c27d5c5dc0f.tar.gz linux-c3466952ca1514158d7c16c9cfc48c27d5c5dc0f.tar.bz2 linux-c3466952ca1514158d7c16c9cfc48c27d5c5dc0f.zip | |
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@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
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/psi.c | 2 |
1 files changed, 1 insertions, 1 deletions
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; |