Glauber Costa wrote:
Commit db64fe02258f1507e13fe5212a989922323685ce broke
KVM (the symptom) for me. The cause is that vmalloc
allocations fail, despite of the fact that /proc/meminfo
shows plenty of vmalloc space available.
After some investigation, it seems to me that the current
way to compute the next addr in the rb-tree transversal
leaves a spare page between each allocation. After a few
allocations, regardless of their size, we run out of vmalloc
space.
while (addr + size >= first->va_start && addr + size <= vend) {
- addr = ALIGN(first->va_end + PAGE_SIZE, align);
+ addr = ALIGN(first->va_end, align);
n = rb_next(&first->rb_node);
if (n)
I'm guessing that the missing comment explains that this is intentional,
to trap buffer overflows?
(okay that was a cheap shot. I don't comment nearly enough either)
Even if you leave a page between allocations, I don't see how you can
fail a one page allocation, unless you've allocated at least N/2 pages
(where N is the size of the vmalloc space in pages).
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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