linux-kernel - Re: Linux 4.7.9

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Message-ID: <20161020091244.GB15710@kroah.com>
Date:   Thu, 20 Oct 2016 11:12:44 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        torvalds@...ux-foundation.org, stable@...r.kernel.org
Cc:     lwn@....net, Jiri Slaby <jslaby@...e.cz>
Subject: Re: Linux 4.7.9

diff --git a/Makefile b/Makefile
index 4e17baa91e9c..cb3f64e40099 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 VERSION = 4
 PATCHLEVEL = 7
-SUBLEVEL = 8
+SUBLEVEL = 9
 EXTRAVERSION =
 NAME = Psychotic Stoned Sheep
 
diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
index ea62245fee26..62900938f26d 100644
--- a/fs/xfs/xfs_xattr.c
+++ b/fs/xfs/xfs_xattr.c
@@ -147,6 +147,7 @@ __xfs_xattr_put_listent(
 	arraytop = context->count + prefix_len + namelen + 1;
 	if (arraytop > context->firstu) {
 		context->count = -1;	/* insufficient space */
+		context->seen_enough = 1;
 		return 0;
 	}
 	offset = (char *)context->alist + context->count;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 317564b11dc7..7c3df8de0fe7 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2194,6 +2194,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma,
 #define FOLL_TRIED	0x800	/* a retry, previous pass started an IO */
 #define FOLL_MLOCK	0x1000	/* lock present pages */
 #define FOLL_REMOTE	0x2000	/* we are working on non-current tsk/mm */
+#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/gup.c b/mm/gup.c
index c057784c8444..2c764f0d71cc 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -60,6 +60,16 @@ static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
 	return -EEXIST;
 }
 
+/*
+ * 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));
+}
+
 static struct page *follow_page_pte(struct vm_area_struct *vma,
 		unsigned long address, pmd_t *pmd, unsigned int flags)
 {
@@ -95,7 +105,7 @@ retry:
 	}
 	if ((flags & FOLL_NUMA) && pte_protnone(pte))
 		goto no_page;
-	if ((flags & FOLL_WRITE) && !pte_write(pte)) {
+	if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, flags)) {
 		pte_unmap_unlock(ptep, ptl);
 		return NULL;
 	}
@@ -409,7 +419,7 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
 	 * reCOWed by userspace write).
 	 */
 	if ((ret & VM_FAULT_WRITE) && !(vma->vm_flags & VM_WRITE))
-		*flags &= ~FOLL_WRITE;
+	        *flags |= FOLL_COW;
 	return 0;
 }