From: Ralph Campbell <rcampbell@nvidia.com>
To: <linux-mm@kvack.org>
Cc: linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org,
dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
"Jérôme Glisse" <jglisse@redhat.com>,
"Jason Gunthorpe" <jgg@mellanox.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Christoph Hellwig" <hch@lst.de>,
"Ralph Campbell" <rcampbell@nvidia.com>
Subject: [PATCH 3/4] mm/hmm: allow hmm_range_fault() of mmap(PROT_NONE)
Date: Wed, 11 Sep 2019 15:28:28 -0700 [thread overview]
Message-ID: <20190911222829.28874-4-rcampbell@nvidia.com> (raw)
In-Reply-To: <20190911222829.28874-1-rcampbell@nvidia.com>
Allow hmm_range_fault() to return success (0) when the range has no access
(!(vma->vm_flags & VM_READ)). The range->pfns[] array will be filled with
range->values[HMM_PFN_NONE] in this case.
This allows the caller to get a snapshot of a range without having to
lookup the vma before calling hmm_range_fault().
If the call to hmm_range_fault() is not a snapshot, the caller can still
check that pfns have the desired access permissions.
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
---
mm/hmm.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/hmm.c b/mm/hmm.c
index 7217912bef13..16c834e5d1c0 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -795,7 +795,9 @@ static int hmm_vma_walk_test(unsigned long start,
*/
if (!(vma->vm_flags & VM_READ)) {
(void) hmm_pfns_fill(start, end, range, HMM_PFN_NONE);
- return -EPERM;
+
+ /* Skip this vma and continue processing the next vma. */
+ return 1;
}
return 0;
--
2.20.1
next prev parent reply other threads:[~2019-09-11 22:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-11 22:28 [PATCH 0/4] HMM tests and minor fixes Ralph Campbell
2019-09-11 22:28 ` [PATCH 1/4] mm/hmm: make full use of walk_page_range() Ralph Campbell
2019-09-12 8:26 ` Christoph Hellwig
2019-09-12 17:16 ` Ralph Campbell
2019-09-11 22:28 ` [PATCH 2/4] mm/hmm: allow snapshot of the special zero page Ralph Campbell
2019-09-12 8:26 ` Christoph Hellwig
2019-09-12 17:08 ` Ralph Campbell
2019-09-11 22:28 ` Ralph Campbell [this message]
2019-09-11 22:28 ` [PATCH 4/4] mm/hmm/test: add self tests for HMM Ralph Campbell
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