linux-kernel - Re: [PATCH] KVM: selftests: Don't assert on exact number of 4KiB in dirty log split test

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Message-ID: <170724571856.385900.17051156735736269281.b4-ty@google.com>
Date: Tue,  6 Feb 2024 13:36:15 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Yi Lai <yi1.lai@...el.com>, Tao Su <tao1.su@...ux.intel.com>
Subject: Re: [PATCH] KVM: selftests: Don't assert on exact number of 4KiB in
 dirty log split test

On Wed, 31 Jan 2024 14:27:28 -0800, Sean Christopherson wrote:
> Drop dirty_log_page_splitting_test's assertion that the number of 4KiB
> pages remains the same across dirty logging being enabled and disabled, as
> the test doesn't guarantee that mappings outside of the memslots being
> dirty logged are stable, e.g. KVM's mappings for code and pages in
> memslot0 can be zapped by things like NUMA balancing.
> 
> To preserve the spirit of the check, assert that (a) the number of 4KiB
> pages after splitting is _at least_ the number of 4KiB pages across all
> memslots under test, and (b) the number of hugepages before splitting adds
> up to the number of pages across all memslots under test.  (b) is a little
> tenuous as it relies on memslot0 being incompatible with transparent
> hugepages, but that holds true for now as selftests explicitly madvise()
> MADV_NOHUGEPAGE for memslot0 (__vm_create() unconditionally specifies the
> backing type as VM_MEM_SRC_ANONYMOUS).
> 
> [...]

Applied to kvm-x86 selftests, with the assert print goof fixed.  Thanks Tao!

[1/1] KVM: selftests: Don't assert on exact number of 4KiB in dirty log split test
      https://github.com/kvm-x86/linux/commit/6fd78beed021

--
https://github.com/kvm-x86/linux/tree/next