[lustre-devel] [PATCH v2 01/29] lustre: llite: ll_fault fixes

[James Simmons <jsimmons@infradead.org>]

From: Patrick Farrell <pfarrell@whamcloud.com>

Various error conditions in the fault path can cause us to
not return a page in vm_fault.  Check if it's present
before accessing it.

Additionally, it's not valid to return VM_FAULT_NOPAGE for
page faults.  The correct return when accessing a page that
does not exist is VM_FAULT_SIGBUS.  Correcting this avoids
looping infinitely in the testcase.

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
WC-bug-id: https://jira.whamcloud.com/browse/LU-11403
Reviewed-on: https://review.whamcloud.com/34247
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Alexander Zarochentsev <c17826@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
---
 fs/lustre/llite/llite_mmap.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/lustre/llite/llite_mmap.c b/fs/lustre/llite/llite_mmap.c
index 1865db1..c8e57ad 100644
--- a/fs/lustre/llite/llite_mmap.c
+++ b/fs/lustre/llite/llite_mmap.c
@@ -238,9 +238,6 @@ static inline vm_fault_t to_fault_error(int result)
 	case 0:
 		result = VM_FAULT_LOCKED;
 		break;
-	case -EFAULT:
-		result = VM_FAULT_NOPAGE;
-		break;
 	case -ENOMEM:
 		result = VM_FAULT_OOM;
 		break;
@@ -366,7 +363,8 @@ static vm_fault_t ll_fault(struct vm_fault *vmf)
 
 restart:
 	result = __ll_fault(vmf->vma, vmf);
-	if (!(result & (VM_FAULT_RETRY | VM_FAULT_ERROR | VM_FAULT_LOCKED))) {
+	if (vmf->page &&
+	    !(result & (VM_FAULT_RETRY | VM_FAULT_ERROR | VM_FAULT_LOCKED))) {
 		struct page *vmpage = vmf->page;
 
 		/* check if this page has been truncated */
-- 
1.8.3.1