Changes representative of linux-3.10.0-327.36.3.el7.tar.xz

kernelim · Oct 20, 2016 · 93c0a44 · 93c0a44
1 parent f8b1d35
commit 93c0a44
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Showing 3 changed files with 13 additions and 3 deletions.
diff --git a/Makefile b/Makefile
@@ -5,7 +5,7 @@ EXTRAVERSION =
 NAME = Unicycling Gorilla
 RHEL_MAJOR = 7
 RHEL_MINOR = 2
-RHEL_RELEASE = 327.36.2
+RHEL_RELEASE = 327.36.3
 RHEL_DRM_VERSION = 4
 RHEL_DRM_PATCHLEVEL = 1
 RHEL_DRM_SUBLEVEL = 0

diff --git a/include/linux/mm.h b/include/linux/mm.h
@@ -1971,6 +1971,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma,
 #define FOLL_NUMA	0x200	/* force NUMA hinting page fault */
 #define FOLL_MIGRATION	0x400	/* wait for page to replace migration entry */
 #define FOLL_TRIED	0x800	/* a retry, previous pass started an IO */
+#define FOLL_COW	0x4000	/* internal GUP flag */
 
 typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,
 			void *data);

diff --git a/mm/memory.c b/mm/memory.c
@@ -131,6 +131,15 @@ static int __init init_zero_pfn(void)
 }
 core_initcall(init_zero_pfn);
 
+/*
+ * FOLL_FORCE can write to even unwritable pte's, but only
+ * after we've gone through a COW cycle and they are dirty.
+ */
+static inline bool can_follow_write_pte(pte_t pte, unsigned int flags)
+{
+	return pte_write(pte) ||
+		((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte));
+}
 
 #if defined(SPLIT_RSS_COUNTING)
 
@@ -1588,7 +1597,7 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
 	}
 	if ((flags & FOLL_NUMA) && pte_numa(pte))
 		goto no_page;
-	if ((flags & FOLL_WRITE) && !pte_write(pte))
+	if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, flags))
 		goto unlock;
 
 	page = vm_normal_page(vma, address, pte);
@@ -1900,7 +1909,7 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 				 */
 				if ((ret & VM_FAULT_WRITE) &&
 				    !(vma->vm_flags & VM_WRITE))
-					foll_flags &= ~FOLL_WRITE;
+					foll_flags |= FOLL_COW;
 
 				cond_resched();
 			}