[RFC PATCH 20/24] x86 fault handler: extend range locking to supported file vmas

From: Michel Lespinasse <walken@google.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	 Laurent Dufour <ldufour@linux.ibm.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	 Matthew Wilcox <willy@infradead.org>,
	"Liam R . Howlett" <Liam.Howlett@oracle.com>,
	 Jerome Glisse <jglisse@redhat.com>,
	Davidlohr Bueso <dave@stgolabs.net>,
	 David Rientjes <rientjes@google.com>
Cc: linux-mm <linux-mm@kvack.org>, Michel Lespinasse <walken@google.com>
Subject: [RFC PATCH 20/24] x86 fault handler: extend range locking to supported file vmas
Date: Mon, 24 Feb 2020 12:30:53 -0800	[thread overview]
Message-ID: <20200224203057.162467-21-walken@google.com> (raw)
In-Reply-To: <20200224203057.162467-1-walken@google.com>

Change the fault handler to operate with a fine grained range lock when
operating on any of the explicitly supported file types.

Signed-off-by: Michel Lespinasse <walken@google.com>
---
 arch/x86/mm/fault.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git arch/x86/mm/fault.c arch/x86/mm/fault.c
index 1e37284d373c..ca30952896e1 100644
--- arch/x86/mm/fault.c
+++ arch/x86/mm/fault.c
@@ -1456,9 +1456,9 @@ void do_user_addr_fault(struct pt_regs *regs,
 
 		/*
 		 * Fall back to locking the entire MM
-		 * when operating on file vma.
+		 * when the vm_ops do not support fine grained range locking.
 		 */
-		if (!vma_is_anonymous(vma)) {
+		if (!vma_is_anonymous(vma) && !vma->vm_ops->fine_grained) {
 			mm_read_range_unlock(mm, range);
 			range = mm_coarse_lock_range();
 			goto retry;
-- 
2.25.0.341.g760bfbb309-goog


