linux-kernel - [PATCH 12/64] fs/userfaultfd: teach userfaultfd_must

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Date:   Mon,  5 Feb 2018 02:27:02 +0100
From:   Davidlohr Bueso <dbueso@...e.de>
To:     akpm@...ux-foundation.org, mingo@...nel.org
Cc:     peterz@...radead.org, ldufour@...ux.vnet.ibm.com, jack@...e.cz,
        mhocko@...nel.org, kirill.shutemov@...ux.intel.com,
        mawilcox@...rosoft.com, mgorman@...hsingularity.net,
        dave@...olabs.net, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH 12/64] fs/userfaultfd: teach userfaultfd_must_wait() about range locking

From: Davidlohr Bueso <dave@...olabs.net>

And make use of mm_is_locked() which is why we pass down the
vmf->lockrange.

Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
 fs/userfaultfd.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index e3089865fd52..883fbffb284e 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -217,13 +217,14 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
 					 struct vm_area_struct *vma,
 					 unsigned long address,
 					 unsigned long flags,
-					 unsigned long reason)
+					 unsigned long reason,
+					 struct range_lock *mmrange)
 {
 	struct mm_struct *mm = ctx->mm;
 	pte_t *pte;
 	bool ret = true;
 
-	VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
+	VM_BUG_ON(!mm_is_locked(mm, mmrange));
 
 	pte = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
 	if (!pte)
@@ -247,7 +248,8 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
 					 struct vm_area_struct *vma,
 					 unsigned long address,
 					 unsigned long flags,
-					 unsigned long reason)
+					 unsigned long reason,
+					 struct range_lock *mmrange)
 {
 	return false;	/* should never get here */
 }
@@ -263,7 +265,8 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
 static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx,
 					 unsigned long address,
 					 unsigned long flags,
-					 unsigned long reason)
+					 unsigned long reason,
+					 struct range_lock *mmrange)
 {
 	struct mm_struct *mm = ctx->mm;
 	pgd_t *pgd;
@@ -273,7 +276,7 @@ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx,
 	pte_t *pte;
 	bool ret = true;
 
-	VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
+	VM_BUG_ON(!mm_is_locked(mm, mmrange));
 
 	pgd = pgd_offset(mm, address);
 	if (!pgd_present(*pgd))
@@ -365,7 +368,7 @@ int handle_userfault(struct vm_fault *vmf, unsigned long reason)
 	 * Coredumping runs without mmap_sem so we can only check that
 	 * the mmap_sem is held, if PF_DUMPCORE was not set.
 	 */
-	WARN_ON_ONCE(!rwsem_is_locked(&mm->mmap_sem));
+	WARN_ON_ONCE(!mm_is_locked(mm, vmf->lockrange));
 
 	ctx = vmf->vma->vm_userfaultfd_ctx.ctx;
 	if (!ctx)
@@ -473,11 +476,12 @@ int handle_userfault(struct vm_fault *vmf, unsigned long reason)
 
 	if (!is_vm_hugetlb_page(vmf->vma))
 		must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags,
-						  reason);
+						  reason, vmf->lockrange);
 	else
 		must_wait = userfaultfd_huge_must_wait(ctx, vmf->vma,
 						       vmf->address,
-						       vmf->flags, reason);
+						       vmf->flags, reason,
+						       vmf->lockrange);
 	up_read(&mm->mmap_sem);
 
 	if (likely(must_wait && !READ_ONCE(ctx->released) &&
-- 
2.13.6