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From: Sean Christopherson <seanjc@google.com>
To: Ricardo Koller <ricarkol@google.com>
Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
	andrew.jones@linux.dev, pbonzini@redhat.com, maz@kernel.org,
	alexandru.elisei@arm.com, eric.auger@redhat.com,
	oupton@google.com, reijiw@google.com, rananta@google.com,
	bgardon@google.com, dmatlack@google.com,
	axelrasmussen@google.com
Subject: Re: [PATCH v8 10/14] KVM: selftests: aarch64: Add aarch64/page_fault_test
Date: Wed, 28 Sep 2022 16:58:53 +0000	[thread overview]
Message-ID: <YzR9TRjVFi+P7UOp@google.com> (raw)
In-Reply-To: <YzPMaEPBtaXguJaT@google.com>

On Tue, Sep 27, 2022, Ricardo Koller wrote:
> On Tue, Sep 27, 2022 at 10:06:23PM +0000, Sean Christopherson wrote:
> > On Mon, Sep 26, 2022, Ricardo Koller wrote:
> > > On Thu, Sep 22, 2022 at 07:32:42PM +0000, Sean Christopherson wrote:
> > > > On Thu, Sep 22, 2022, Ricardo Koller wrote:
> > > > > +	void *hva = (void *)region->region.userspace_addr;
> > > > > +	uint64_t paging_size = region->region.memory_size;
> > > > > +	int ret, fd = region->fd;
> > > > > +
> > > > > +	if (fd != -1) {
> > > > > +		ret = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
> > > > > +				0, paging_size);
> > > > > +		TEST_ASSERT(ret == 0, "fallocate failed, errno: %d\n", errno);
> > > > > +	} else {
> > > > > +		if (is_backing_src_hugetlb(region->backing_src_type))
> > > > > +			return false;
> > > > 
> > > > Why is hugetlb disallowed?  I thought anon hugetlb supports MADV_DONTNEED?
> > > > 
> > > 
> > > It fails with EINVAL (only tried on arm) for both the PAGE_SIZE and the huge
> > > page size. And note that the address is aligned as well.
> > > 
> > > madvise(0xffffb7c00000, 2097152, MADV_DONTNEED) = -1 EINVAL (Invalid argument)
> > > 	^^^^^^^^^^^^^^	^^^^^^^
> > > 	2M aligned	2M (hugepage size)
> > > 			
> > > madvise(0xffff9e800000, 4096, MADV_DONTNEED) = -1 EINVAL (Invalid argument)   
> > > 			^^^^
> > > 			PAGE_SIZE
> > 
> > I think this needs to be root caused before merging.  Unless I'm getting turned
> > around, MADV_DONTEED should work, i.e. there is a test bug lurking somewhere.
> 
> Turns out that the failure is documented. Found this in the madvise manpage:
> 
>   MADV_DONTNEED cannot be applied to locked pages, Huge TLB pages, or VM_PFNMAP pages.

The manpages are stale:

   c4b6cb884011 ("selftests/vm: add hugetlb madvise MADV_DONTNEED MADV_REMOVE test")
   90e7e7f5ef3f ("mm: enable MADV_DONTNEED for hugetlb mappings")

The tools/testing/selftests/vm/hugetlb-madvise.c selftest effectively tests what
is being done here, so _something_ is broken.

WARNING: multiple messages have this Message-ID (diff)
From: Sean Christopherson <seanjc@google.com>
To: Ricardo Koller <ricarkol@google.com>
Cc: kvm@vger.kernel.org, maz@kernel.org, bgardon@google.com,
	andrew.jones@linux.dev, dmatlack@google.com, pbonzini@redhat.com,
	axelrasmussen@google.com, kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH v8 10/14] KVM: selftests: aarch64: Add aarch64/page_fault_test
Date: Wed, 28 Sep 2022 16:58:53 +0000	[thread overview]
Message-ID: <YzR9TRjVFi+P7UOp@google.com> (raw)
In-Reply-To: <YzPMaEPBtaXguJaT@google.com>

On Tue, Sep 27, 2022, Ricardo Koller wrote:
> On Tue, Sep 27, 2022 at 10:06:23PM +0000, Sean Christopherson wrote:
> > On Mon, Sep 26, 2022, Ricardo Koller wrote:
> > > On Thu, Sep 22, 2022 at 07:32:42PM +0000, Sean Christopherson wrote:
> > > > On Thu, Sep 22, 2022, Ricardo Koller wrote:
> > > > > +	void *hva = (void *)region->region.userspace_addr;
> > > > > +	uint64_t paging_size = region->region.memory_size;
> > > > > +	int ret, fd = region->fd;
> > > > > +
> > > > > +	if (fd != -1) {
> > > > > +		ret = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
> > > > > +				0, paging_size);
> > > > > +		TEST_ASSERT(ret == 0, "fallocate failed, errno: %d\n", errno);
> > > > > +	} else {
> > > > > +		if (is_backing_src_hugetlb(region->backing_src_type))
> > > > > +			return false;
> > > > 
> > > > Why is hugetlb disallowed?  I thought anon hugetlb supports MADV_DONTNEED?
> > > > 
> > > 
> > > It fails with EINVAL (only tried on arm) for both the PAGE_SIZE and the huge
> > > page size. And note that the address is aligned as well.
> > > 
> > > madvise(0xffffb7c00000, 2097152, MADV_DONTNEED) = -1 EINVAL (Invalid argument)
> > > 	^^^^^^^^^^^^^^	^^^^^^^
> > > 	2M aligned	2M (hugepage size)
> > > 			
> > > madvise(0xffff9e800000, 4096, MADV_DONTNEED) = -1 EINVAL (Invalid argument)   
> > > 			^^^^
> > > 			PAGE_SIZE
> > 
> > I think this needs to be root caused before merging.  Unless I'm getting turned
> > around, MADV_DONTEED should work, i.e. there is a test bug lurking somewhere.
> 
> Turns out that the failure is documented. Found this in the madvise manpage:
> 
>   MADV_DONTNEED cannot be applied to locked pages, Huge TLB pages, or VM_PFNMAP pages.

The manpages are stale:

   c4b6cb884011 ("selftests/vm: add hugetlb madvise MADV_DONTNEED MADV_REMOVE test")
   90e7e7f5ef3f ("mm: enable MADV_DONTNEED for hugetlb mappings")

The tools/testing/selftests/vm/hugetlb-madvise.c selftest effectively tests what
is being done here, so _something_ is broken.
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  reply	other threads:[~2022-09-28 16:59 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-22  3:18 [PATCH v8 00/14] KVM: selftests: Add aarch64/page_fault_test Ricardo Koller
2022-09-22  3:18 ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 01/14] KVM: selftests: Add a userfaultfd library Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 02/14] KVM: selftests: aarch64: Add virt_get_pte_hva() library function Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 03/14] KVM: selftests: Add missing close and munmap in __vm_mem_region_delete() Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 04/14] KVM: selftests: aarch64: Construct DEFAULT_MAIR_EL1 using sysreg.h macros Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 05/14] tools: Copy bitfield.h from the kernel sources Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 06/14] KVM: selftests: Stash backing_src_type in struct userspace_mem_region Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 07/14] KVM: selftests: Add vm->memslots[] and enum kvm_mem_region_type Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22 18:33   ` Sean Christopherson
2022-09-22 18:33     ` Sean Christopherson
2022-09-22  3:18 ` [PATCH v8 08/14] KVM: selftests: Fix alignment in virt_arch_pgd_alloc() and vm_vaddr_alloc() Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 09/14] KVM: selftests: Use the right memslot for code, page-tables, and data allocations Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22 18:36   ` Sean Christopherson
2022-09-22 18:36     ` Sean Christopherson
2022-09-22  3:18 ` [PATCH v8 10/14] KVM: selftests: aarch64: Add aarch64/page_fault_test Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22 19:32   ` Sean Christopherson
2022-09-22 19:32     ` Sean Christopherson
2022-09-26 17:22     ` Ricardo Koller
2022-09-26 17:22       ` Ricardo Koller
2022-09-27 22:06       ` Sean Christopherson
2022-09-27 22:06         ` Sean Christopherson
2022-09-28  4:24         ` Ricardo Koller
2022-09-28  4:24           ` Ricardo Koller
2022-09-28 16:58           ` Sean Christopherson [this message]
2022-09-28 16:58             ` Sean Christopherson
2022-09-28 18:10             ` Ricardo Koller
2022-09-28 18:10               ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 11/14] KVM: selftests: aarch64: Add userfaultfd tests into page_fault_test Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 12/14] KVM: selftests: aarch64: Add dirty logging " Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 13/14] KVM: selftests: aarch64: Add readonly memslot " Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller
2022-09-22  3:18 ` [PATCH v8 14/14] KVM: selftests: aarch64: Add mix of " Ricardo Koller
2022-09-22  3:18   ` Ricardo Koller

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