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From:   Christoph Hellwig <hch@lst.de>
To:     Dan Williams <dan.j.williams@intel.com>,
        =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= <jglisse@redhat.com>,
        Jason Gunthorpe <jgg@mellanox.com>,
        Ben Skeggs <bskeggs@redhat.com>
Cc:     Ira Weiny <ira.weiny@intel.com>, linux-mm@kvack.org,
        nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-nvdimm@lists.01.org, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        "Kuehling, Felix" <Felix.Kuehling@amd.com>
Subject: [PATCH 05/22] mm/hmm: Only set FAULT_FLAG_ALLOW_RETRY for non-blocking
Date:   Mon,  1 Jul 2019 08:20:03 +0200
Message-Id: <20190701062020.19239-6-hch@lst.de>
In-Reply-To: <20190701062020.19239-1-hch@lst.de>
References: <20190701062020.19239-1-hch@lst.de>
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From: "Kuehling, Felix" <Felix.Kuehling@amd.com>

Don't set this flag by default in hmm_vma_do_fault. It is set
conditionally just a few lines below. Setting it unconditionally can lead
to handle_mm_fault doing a non-blocking fault, returning -EBUSY and
unlocking mmap_sem unexpectedly.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
---
 mm/hmm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index dce4e70e648a..826816ab2377 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -328,7 +328,7 @@ struct hmm_vma_walk {
 static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr,
 			    bool write_fault, uint64_t *pfn)
 {
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_REMOTE;
+	unsigned int flags = FAULT_FLAG_REMOTE;
 	struct hmm_vma_walk *hmm_vma_walk = walk->private;
 	struct hmm_range *range = hmm_vma_walk->range;
 	struct vm_area_struct *vma = walk->vma;
-- 
2.20.1