mm/gup: remove task_struct pointer for all gup code

After the cleanup of page fault accounting, gup does not need to pass
task_struct around any more.  Remove that parameter in the whole gup
stack.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Link: http://lkml.kernel.org/r/20200707225021.200906-26-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 44 insertions, 61 deletions

diff --git a/mm/gup.c b/mm/gup.c
index d5d44c68fa19..39e58df6925d 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -859,7 +859,7 @@ unmap:
  * does not include FOLL_NOWAIT, the mmap_lock may be released.  If it
  * is, *@locked will be set to 0 and -EBUSY returned.
  */
-static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
+static int faultin_page(struct vm_area_struct *vma,
 		unsigned long address, unsigned int *flags, int *locked)
 {
 	unsigned int fault_flags = 0;
@@ -962,7 +962,6 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
 
 /**
  * __get_user_pages() - pin user pages in memory
- * @tsk:	task_struct of target task
  * @mm:		mm_struct of target mm
  * @start:	starting user address
  * @nr_pages:	number of pages from start to pin
@@ -1021,7 +1020,7 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
  * instead of __get_user_pages. __get_user_pages should be used only if
  * you need some special @gup_flags.
  */
-static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+static long __get_user_pages(struct mm_struct *mm,
 		unsigned long start, unsigned long nr_pages,
 		unsigned int gup_flags, struct page **pages,
 		struct vm_area_struct **vmas, int *locked)
@@ -1103,8 +1102,7 @@ retry:
 
 		page = follow_page_mask(vma, start, foll_flags, &ctx);
 		if (!page) {
-			ret = faultin_page(tsk, vma, start, &foll_flags,
-					   locked);
+			ret = faultin_page(vma, start, &foll_flags, locked);
 			switch (ret) {
 			case 0:
 				goto retry;
@@ -1178,8 +1176,6 @@ static bool vma_permits_fault(struct vm_area_struct *vma,
 
 /**
  * fixup_user_fault() - manually resolve a user page fault
- * @tsk:	the task_struct to use for page fault accounting, or
- *		NULL if faults are not to be recorded.
  * @mm:		mm_struct of target mm
  * @address:	user address
  * @fault_flags:flags to pass down to handle_mm_fault()
@@ -1207,7 +1203,7 @@ static bool vma_permits_fault(struct vm_area_struct *vma,
  * This function will not return with an unlocked mmap_lock. So it has not the
  * same semantics wrt the @mm->mmap_lock as does filemap_fault().
  */
-int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
+int fixup_user_fault(struct mm_struct *mm,
 		     unsigned long address, unsigned int fault_flags,
 		     bool *unlocked)
 {
@@ -1256,8 +1252,7 @@ EXPORT_SYMBOL_GPL(fixup_user_fault);
  * Please note that this function, unlike __get_user_pages will not
  * return 0 for nr_pages > 0 without FOLL_NOWAIT
  */
-static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
-						struct mm_struct *mm,
+static __always_inline long __get_user_pages_locked(struct mm_struct *mm,
 						unsigned long start,
 						unsigned long nr_pages,
 						struct page **pages,
@@ -1290,7 +1285,7 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 	pages_done = 0;
 	lock_dropped = false;
 	for (;;) {
-		ret = __get_user_pages(tsk, mm, start, nr_pages, flags, pages,
+		ret = __get_user_pages(mm, start, nr_pages, flags, pages,
 				       vmas, locked);
 		if (!locked)
 			/* VM_FAULT_RETRY couldn't trigger, bypass */
@@ -1350,7 +1345,7 @@ retry:
 		}
 
 		*locked = 1;
-		ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED,
+		ret = __get_user_pages(mm, start, 1, flags | FOLL_TRIED,
 				       pages, NULL, locked);
 		if (!*locked) {
 			/* Continue to retry until we succeeded */
@@ -1437,7 +1432,7 @@ long populate_vma_page_range(struct vm_area_struct *vma,
 	 * We made sure addr is within a VMA, so the following will
 	 * not result in a stack expansion that recurses back here.
 	 */
-	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
+	return __get_user_pages(mm, start, nr_pages, gup_flags,
 				NULL, NULL, locked);
 }
 
@@ -1521,7 +1516,7 @@ struct page *get_dump_page(unsigned long addr)
 	struct vm_area_struct *vma;
 	struct page *page;
 
-	if (__get_user_pages(current, current->mm, addr, 1,
+	if (__get_user_pages(current->mm, addr, 1,
 			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
 			     NULL) < 1)
 		return NULL;
@@ -1530,8 +1525,7 @@ struct page *get_dump_page(unsigned long addr)
 }
 #endif /* CONFIG_ELF_CORE */
 #else /* CONFIG_MMU */
-static long __get_user_pages_locked(struct task_struct *tsk,
-		struct mm_struct *mm, unsigned long start,
+static long __get_user_pages_locked(struct mm_struct *mm, unsigned long start,
 		unsigned long nr_pages, struct page **pages,
 		struct vm_area_struct **vmas, int *locked,
 		unsigned int foll_flags)
@@ -1596,8 +1590,7 @@ static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
 }
 
 #ifdef CONFIG_CMA
-static long check_and_migrate_cma_pages(struct task_struct *tsk,
-					struct mm_struct *mm,
+static long check_and_migrate_cma_pages(struct mm_struct *mm,
 					unsigned long start,
 					unsigned long nr_pages,
 					struct page **pages,
@@ -1675,7 +1668,7 @@ check_again:
 		 * again migrating any new CMA pages which we failed to isolate
 		 * earlier.
 		 */
-		ret = __get_user_pages_locked(tsk, mm, start, nr_pages,
+		ret = __get_user_pages_locked(mm, start, nr_pages,
 						   pages, vmas, NULL,
 						   gup_flags);
 
@@ -1689,8 +1682,7 @@ check_again:
 	return ret;
 }
 #else
-static long check_and_migrate_cma_pages(struct task_struct *tsk,
-					struct mm_struct *mm,
+static long check_and_migrate_cma_pages(struct mm_struct *mm,
 					unsigned long start,
 					unsigned long nr_pages,
 					struct page **pages,
@@ -1705,8 +1697,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
  * __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
  * allows us to process the FOLL_LONGTERM flag.
  */
-static long __gup_longterm_locked(struct task_struct *tsk,
-				  struct mm_struct *mm,
+static long __gup_longterm_locked(struct mm_struct *mm,
 				  unsigned long start,
 				  unsigned long nr_pages,
 				  struct page **pages,
@@ -1731,7 +1722,7 @@ static long __gup_longterm_locked(struct task_struct *tsk,
 		flags = memalloc_nocma_save();
 	}
 
-	rc = __get_user_pages_locked(tsk, mm, start, nr_pages, pages,
+	rc = __get_user_pages_locked(mm, start, nr_pages, pages,
 				     vmas_tmp, NULL, gup_flags);
 
 	if (gup_flags & FOLL_LONGTERM) {
@@ -1745,7 +1736,7 @@ static long __gup_longterm_locked(struct task_struct *tsk,
 			goto out;
 		}
 
-		rc = check_and_migrate_cma_pages(tsk, mm, start, rc, pages,
+		rc = check_and_migrate_cma_pages(mm, start, rc, pages,
 						 vmas_tmp, gup_flags);
 out:
 		memalloc_nocma_restore(flags);
@@ -1756,22 +1747,20 @@ out:
 	return rc;
 }
 #else /* !CONFIG_FS_DAX && !CONFIG_CMA */
-static __always_inline long __gup_longterm_locked(struct task_struct *tsk,
-						  struct mm_struct *mm,
+static __always_inline long __gup_longterm_locked(struct mm_struct *mm,
 						  unsigned long start,
 						  unsigned long nr_pages,
 						  struct page **pages,
 						  struct vm_area_struct **vmas,
 						  unsigned int flags)
 {
-	return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
+	return __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
 				       NULL, flags);
 }
 #endif /* CONFIG_FS_DAX || CONFIG_CMA */
 
 #ifdef CONFIG_MMU
-static long __get_user_pages_remote(struct task_struct *tsk,
-				    struct mm_struct *mm,
+static long __get_user_pages_remote(struct mm_struct *mm,
 				    unsigned long start, unsigned long nr_pages,
 				    unsigned int gup_flags, struct page **pages,
 				    struct vm_area_struct **vmas, int *locked)
@@ -1790,20 +1779,18 @@ static long __get_user_pages_remote(struct task_struct *tsk,
 		 * This will check the vmas (even if our vmas arg is NULL)
 		 * and return -ENOTSUPP if DAX isn't allowed in this case:
 		 */
-		return __gup_longterm_locked(tsk, mm, start, nr_pages, pages,
+		return __gup_longterm_locked(mm, start, nr_pages, pages,
 					     vmas, gup_flags | FOLL_TOUCH |
 					     FOLL_REMOTE);
 	}
 
-	return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
+	return __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
 				       locked,
 				       gup_flags | FOLL_TOUCH | FOLL_REMOTE);
 }
 
 /**
  * get_user_pages_remote() - pin user pages in memory
- * @tsk:	the task_struct to use for page fault accounting, or
- *		NULL if faults are not to be recorded.
  * @mm:		mm_struct of target mm
  * @start:	starting user address
  * @nr_pages:	number of pages from start to pin
@@ -1862,7 +1849,7 @@ static long __get_user_pages_remote(struct task_struct *tsk,
  * should use get_user_pages_remote because it cannot pass
  * FAULT_FLAG_ALLOW_RETRY to handle_mm_fault.
  */
-long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
+long get_user_pages_remote(struct mm_struct *mm,
 		unsigned long start, unsigned long nr_pages,
 		unsigned int gup_flags, struct page **pages,
 		struct vm_area_struct **vmas, int *locked)
@@ -1874,13 +1861,13 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 	if (WARN_ON_ONCE(gup_flags & FOLL_PIN))
 		return -EINVAL;
 
-	return __get_user_pages_remote(tsk, mm, start, nr_pages, gup_flags,
+	return __get_user_pages_remote(mm, start, nr_pages, gup_flags,
 				       pages, vmas, locked);
 }
 EXPORT_SYMBOL(get_user_pages_remote);
 
 #else /* CONFIG_MMU */
-long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
+long get_user_pages_remote(struct mm_struct *mm,
 			   unsigned long start, unsigned long nr_pages,
 			   unsigned int gup_flags, struct page **pages,
 			   struct vm_area_struct **vmas, int *locked)
@@ -1888,8 +1875,7 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 	return 0;
 }
 
-static long __get_user_pages_remote(struct task_struct *tsk,
-				    struct mm_struct *mm,
+static long __get_user_pages_remote(struct mm_struct *mm,
 				    unsigned long start, unsigned long nr_pages,
 				    unsigned int gup_flags, struct page **pages,
 				    struct vm_area_struct **vmas, int *locked)
@@ -1909,11 +1895,10 @@ static long __get_user_pages_remote(struct task_struct *tsk,
  * @vmas:       array of pointers to vmas corresponding to each page.
  *              Or NULL if the caller does not require them.
  *
- * This is the same as get_user_pages_remote(), just with a
- * less-flexible calling convention where we assume that the task
- * and mm being operated on are the current task's and don't allow
- * passing of a locked parameter.  We also obviously don't pass
- * FOLL_REMOTE in here.
+ * This is the same as get_user_pages_remote(), just with a less-flexible
+ * calling convention where we assume that the mm being operated on belongs to
+ * the current task, and doesn't allow passing of a locked parameter.  We also
+ * obviously don't pass FOLL_REMOTE in here.
  */
 long get_user_pages(unsigned long start, unsigned long nr_pages,
 		unsigned int gup_flags, struct page **pages,
@@ -1926,7 +1911,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 	if (WARN_ON_ONCE(gup_flags & FOLL_PIN))
 		return -EINVAL;
 
-	return __gup_longterm_locked(current, current->mm, start, nr_pages,
+	return __gup_longterm_locked(current->mm, start, nr_pages,
 				     pages, vmas, gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages);
@@ -1936,7 +1921,7 @@ EXPORT_SYMBOL(get_user_pages);
  *
  *      mmap_read_lock(mm);
  *      do_something()
- *      get_user_pages(tsk, mm, ..., pages, NULL);
+ *      get_user_pages(mm, ..., pages, NULL);
  *      mmap_read_unlock(mm);
  *
  *  to:
@@ -1944,7 +1929,7 @@ EXPORT_SYMBOL(get_user_pages);
  *      int locked = 1;
  *      mmap_read_lock(mm);
  *      do_something()
- *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
+ *      get_user_pages_locked(mm, ..., pages, &locked);
  *      if (locked)
  *          mmap_read_unlock(mm);
  *
@@ -1982,7 +1967,7 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 	if (WARN_ON_ONCE(gup_flags & FOLL_PIN))
 		return -EINVAL;
 
-	return __get_user_pages_locked(current, current->mm, start, nr_pages,
+	return __get_user_pages_locked(current->mm, start, nr_pages,
 				       pages, NULL, locked,
 				       gup_flags | FOLL_TOUCH);
 }
@@ -1992,12 +1977,12 @@ EXPORT_SYMBOL(get_user_pages_locked);
  * get_user_pages_unlocked() is suitable to replace the form:
  *
  *      mmap_read_lock(mm);
- *      get_user_pages(tsk, mm, ..., pages, NULL);
+ *      get_user_pages(mm, ..., pages, NULL);
  *      mmap_read_unlock(mm);
  *
  *  with:
  *
- *      get_user_pages_unlocked(tsk, mm, ..., pages);
+ *      get_user_pages_unlocked(mm, ..., pages);
  *
  * It is functionally equivalent to get_user_pages_fast so
  * get_user_pages_fast should be used instead if specific gup_flags
@@ -2020,7 +2005,7 @@ long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 		return -EINVAL;
 
 	mmap_read_lock(mm);
-	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
+	ret = __get_user_pages_locked(mm, start, nr_pages, pages, NULL,
 				      &locked, gup_flags | FOLL_TOUCH);
 	if (locked)
 		mmap_read_unlock(mm);
@@ -2665,7 +2650,7 @@ static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
 	 */
 	if (gup_flags & FOLL_LONGTERM) {
 		mmap_read_lock(current->mm);
-		ret = __gup_longterm_locked(current, current->mm,
+		ret = __gup_longterm_locked(current->mm,
 					    start, nr_pages,
 					    pages, NULL, gup_flags);
 		mmap_read_unlock(current->mm);
@@ -2908,10 +2893,8 @@ int pin_user_pages_fast_only(unsigned long start, int nr_pages,
 EXPORT_SYMBOL_GPL(pin_user_pages_fast_only);
 
 /**
- * pin_user_pages_remote() - pin pages of a remote process (task != current)
+ * pin_user_pages_remote() - pin pages of a remote process
  *
- * @tsk:	the task_struct to use for page fault accounting, or
- *		NULL if faults are not to be recorded.
  * @mm:		mm_struct of target mm
  * @start:	starting user address
  * @nr_pages:	number of pages from start to pin
@@ -2932,7 +2915,7 @@ EXPORT_SYMBOL_GPL(pin_user_pages_fast_only);
  * FOLL_PIN means that the pages must be released via unpin_user_page(). Please
  * see Documentation/core-api/pin_user_pages.rst for details.
  */
-long pin_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
+long pin_user_pages_remote(struct mm_struct *mm,
 			   unsigned long start, unsigned long nr_pages,
 			   unsigned int gup_flags, struct page **pages,
 			   struct vm_area_struct **vmas, int *locked)
@@ -2942,7 +2925,7 @@ long pin_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 		return -EINVAL;
 
 	gup_flags |= FOLL_PIN;
-	return __get_user_pages_remote(tsk, mm, start, nr_pages, gup_flags,
+	return __get_user_pages_remote(mm, start, nr_pages, gup_flags,
 				       pages, vmas, locked);
 }
 EXPORT_SYMBOL(pin_user_pages_remote);
@@ -2974,7 +2957,7 @@ long pin_user_pages(unsigned long start, unsigned long nr_pages,
 		return -EINVAL;
 
 	gup_flags |= FOLL_PIN;
-	return __gup_longterm_locked(current, current->mm, start, nr_pages,
+	return __gup_longterm_locked(current->mm, start, nr_pages,
 				     pages, vmas, gup_flags);
 }
 EXPORT_SYMBOL(pin_user_pages);
@@ -3019,7 +3002,7 @@ long pin_user_pages_locked(unsigned long start, unsigned long nr_pages,
 		return -EINVAL;
 
 	gup_flags |= FOLL_PIN;
-	return __get_user_pages_locked(current, current->mm, start, nr_pages,
+	return __get_user_pages_locked(current->mm, start, nr_pages,
 				       pages, NULL, locked,
 				       gup_flags | FOLL_TOUCH);
 }
diff --git a/mm/memory.c b/mm/memory.c
index 2b7f0e00f312..228efaca75d3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4742,7 +4742,7 @@ int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
 		void *maddr;
 		struct page *page = NULL;
 
-		ret = get_user_pages_remote(tsk, mm, addr, 1,
+		ret = get_user_pages_remote(mm, addr, 1,
 				gup_flags, &page, &vma, NULL);
 		if (ret <= 0) {
 #ifndef CONFIG_HAVE_IOREMAP_PROT
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index cc85ce81914a..29c052099aff 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -105,7 +105,7 @@ static int process_vm_rw_single_vec(unsigned long addr,
 		 * current/current->mm
 		 */
 		mmap_read_lock(mm);
-		pinned_pages = pin_user_pages_remote(task, mm, pa, pinned_pages,
+		pinned_pages = pin_user_pages_remote(mm, pa, pinned_pages,
 						     flags, process_pages,
 						     NULL, &locked);
 		if (locked)