Messages in this thread | | | From | Nadav Amit <> | Subject | Re: [RFC PATCH v5 6/8] drivers: vmware: balloon - report inflated memory | Date | Fri, 21 Oct 2022 06:50:33 +0000 |
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On Oct 19, 2022, at 12:56 PM, Alexander Atanasov <alexander.atanasov@virtuozzo.com> wrote:
> Update the inflated memory in the mm core on change. > > Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com> > --- > drivers/misc/vmw_balloon.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c > index 91d4d2a285c5..3bfd845898f5 100644 > --- a/drivers/misc/vmw_balloon.c > +++ b/drivers/misc/vmw_balloon.c > @@ -1507,6 +1507,7 @@ static void vmballoon_work(struct work_struct *work) > queue_delayed_work(system_freezable_wq, > dwork, round_jiffies_relative(HZ)); > > + balloon_set_inflated_free(atomic64_read(&b->size) << 2); > }
I don’t like it in general (I think that something like that should go into some common infra).
But more concretely there are at least 2 problems here. First, queueing the work should come last. Second, there are other places that change the balloon size (e.g., vmballoon_reset()), which are not handled by this patch.
If you added calls to balloon_set_inflated_free() from these places, you can get races while calling balloon_set_inflated_free() and the last value that would be latched would be the wrong one. I don’t see anything in the logic or comments that clarify how something like that should be resolved.
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