Re: [PATCH] kvm/arm: return 0 when the number of objects is not lessthan min

On Thu, Dec 06, 2018 at 09:56:30AM +0800, peng.hao2@zte.com.cn wrote:

quoted

On Wed, Dec 05, 2018 at 09:15:51AM +0800, Peng Hao wrote:

quoted

Return 0 when there is enough kvm_mmu_memory_cache object.

Signed-off-by: Peng Hao <redacted>
---
 virt/kvm/arm/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index ed162a6..fcda0ce 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c

@@ -127,7 +127,7 @@ static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
     while (cache->nobjs < max) {
         page = (void *)__get_free_page(PGALLOC_GFP);
         if (!page)
-            return -ENOMEM;
+            return cache->nobjs >= min ? 0 : -ENOMEM;

This condition will never be true here, as the exact same condition is
already checked above, and if it had been true, then we wouldn't be here.

What problem are you attempting to solve?

if (cache->nobjs >= min)                      ------here cache->nobjs<min,it can continue downward 
     return 0;
while (cache->nobjs < max) {
    page = (void *)__get_free_page(PGALLOC_GFP);
    if (!page)
       return -ENOMEM;                         -----here it is possible that  (cache->nobjs >= min) and (cache->nobjs<max)
    cache->objects[cache->nobjs++] = page; ---here cache->nobjs increasing
  }

I just think the logic of this function is to return 0 as long as (cache->nobjs >= min).
thanks.

Oh, I see now. This is the case where we can do enough allocating to over
the min line, but fail before we get to the max.

Thanks,
drew

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