Merge tag 'docs-4.18' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "There's been a fair amount of work in the docs tree this time around,
  including:

   - Extensive RST conversions and organizational work in the
     memory-management docs thanks to Mike Rapoport.

   - An update of Documentation/features from Andrea Parri and a script
     to keep it updated.

   - Various LICENSES updates from Thomas, along with a script to check
     SPDX tags.

   - Work to fix dangling references to documentation files; this
     involved a fair number of one-liner comment changes outside of
     Documentation/

  ... and the usual list of documentation improvements, typo fixes, etc"

* tag 'docs-4.18' of git://git.lwn.net/linux: (103 commits)
  Documentation: document hung_task_panic kernel parameter
  docs/admin-guide/mm: add high level concepts overview
  docs/vm: move ksm and transhuge from "user" to "internals" section.
  docs: Use the kerneldoc comments for memalloc_no*()
  doc: document scope NOFS, NOIO APIs
  docs: update kernel versions and dates in tables
  docs/vm: transhuge: split userspace bits to admin-guide/mm/transhuge
  docs/vm: transhuge: minor updates
  docs/vm: transhuge: change sections order
  Documentation: arm: clean up Marvell Berlin family info
  Documentation: gpio: driver: Fix a typo and some odd grammar
  docs: ranoops.rst: fix location of ramoops.txt
  scripts/documentation-file-ref-check: rewrite it in perl with auto-fix mode
  docs: uio-howto.rst: use a code block to solve a warning
  mm, THP, doc: Add document for thp_swpout/thp_swpout_fallback
  w1: w1_io.c: fix a kernel-doc warning
  Documentation/process/posting: wrap text at 80 cols
  docs: admin-guide: add cgroup-v2 documentation
  Revert "Documentation/features/vm: Remove arch support status file for 'pte_special'"
  Documentation: refcount-vs-atomic: Update reference to LKMM doc.
  ...

5 files changed, 45 insertions, 7 deletions

diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 39988924de3a..2f1327c37a63 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -16,7 +16,7 @@
 /*
  * Heterogeneous Memory Management (HMM)
  *
- * See Documentation/vm/hmm.txt for reasons and overview of what HMM is and it
+ * See Documentation/vm/hmm.rst for reasons and overview of what HMM is and it
  * is for. Here we focus on the HMM API description, with some explanation of
  * the underlying implementation.
  *
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 7b4899c06f49..74ea5e2310a8 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -45,7 +45,7 @@ struct vmem_altmap {
  * must be treated as an opaque object, rather than a "normal" struct page.
  *
  * A more complete discussion of unaddressable memory may be found in
- * include/linux/hmm.h and Documentation/vm/hmm.txt.
+ * include/linux/hmm.h and Documentation/vm/hmm.rst.
  *
  * MEMORY_DEVICE_PUBLIC:
  * Device memory that is cache coherent from device and CPU point of view. This
@@ -67,7 +67,7 @@ enum memory_type {
  *   page_free()
  *
  * Additional notes about MEMORY_DEVICE_PRIVATE may be found in
- * include/linux/hmm.h and Documentation/vm/hmm.txt. There is also a brief
+ * include/linux/hmm.h and Documentation/vm/hmm.rst. There is also a brief
  * explanation in include/linux/memory_hotplug.h.
  *
  * The page_fault() callback must migrate page back, from device memory to
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 2d07a1ed5a31..392e6af82701 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -174,7 +174,7 @@ struct mmu_notifier_ops {
 	 * invalidate_range_start()/end() notifiers, as
 	 * invalidate_range() alread catches the points in time when an
 	 * external TLB range needs to be flushed. For more in depth
-	 * discussion on this see Documentation/vm/mmu_notifier.txt
+	 * discussion on this see Documentation/vm/mmu_notifier.rst
 	 *
 	 * Note that this function might be called with just a sub-range
 	 * of what was passed to invalidate_range_start()/end(), if
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 2c570cd934af..76a8cb4ef178 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -28,7 +28,7 @@ extern struct mm_struct *mm_alloc(void);
  *
  * Use mmdrop() to release the reference acquired by mmgrab().
  *
- * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
+ * See also <Documentation/vm/active_mm.rst> for an in-depth explanation
  * of &mm_struct.mm_count vs &mm_struct.mm_users.
  */
 static inline void mmgrab(struct mm_struct *mm)
@@ -62,7 +62,7 @@ static inline void mmdrop(struct mm_struct *mm)
  *
  * Use mmput() to release the reference acquired by mmget().
  *
- * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
+ * See also <Documentation/vm/active_mm.rst> for an in-depth explanation
  * of &mm_struct.mm_count vs &mm_struct.mm_users.
  */
 static inline void mmget(struct mm_struct *mm)
@@ -170,6 +170,17 @@ static inline void fs_reclaim_acquire(gfp_t gfp_mask) { }
 static inline void fs_reclaim_release(gfp_t gfp_mask) { }
 #endif
 
+/**
+ * memalloc_noio_save - Marks implicit GFP_NOIO allocation scope.
+ *
+ * This functions marks the beginning of the GFP_NOIO allocation scope.
+ * All further allocations will implicitly drop __GFP_IO flag and so
+ * they are safe for the IO critical section from the allocation recursion
+ * point of view. Use memalloc_noio_restore to end the scope with flags
+ * returned by this function.
+ *
+ * This function is safe to be used from any context.
+ */
 static inline unsigned int memalloc_noio_save(void)
 {
 	unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
@@ -177,11 +188,30 @@ static inline unsigned int memalloc_noio_save(void)
 	return flags;
 }
 
+/**
+ * memalloc_noio_restore - Ends the implicit GFP_NOIO scope.
+ * @flags: Flags to restore.
+ *
+ * Ends the implicit GFP_NOIO scope started by memalloc_noio_save function.
+ * Always make sure that that the given flags is the return value from the
+ * pairing memalloc_noio_save call.
+ */
 static inline void memalloc_noio_restore(unsigned int flags)
 {
 	current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
 }
 
+/**
+ * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope.
+ *
+ * This functions marks the beginning of the GFP_NOFS allocation scope.
+ * All further allocations will implicitly drop __GFP_FS flag and so
+ * they are safe for the FS critical section from the allocation recursion
+ * point of view. Use memalloc_nofs_restore to end the scope with flags
+ * returned by this function.
+ *
+ * This function is safe to be used from any context.
+ */
 static inline unsigned int memalloc_nofs_save(void)
 {
 	unsigned int flags = current->flags & PF_MEMALLOC_NOFS;
@@ -189,6 +219,14 @@ static inline unsigned int memalloc_nofs_save(void)
 	return flags;
 }
 
+/**
+ * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope.
+ * @flags: Flags to restore.
+ *
+ * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function.
+ * Always make sure that that the given flags is the return value from the
+ * pairing memalloc_nofs_save call.
+ */
 static inline void memalloc_nofs_restore(unsigned int flags)
 {
 	current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags;
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 2417d288e016..c063443d8638 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -53,7 +53,7 @@ static inline int current_is_kswapd(void)
 
 /*
  * Unaddressable device memory support. See include/linux/hmm.h and
- * Documentation/vm/hmm.txt. Short description is we need struct pages for
+ * Documentation/vm/hmm.rst. Short description is we need struct pages for
  * device memory that is unaddressable (inaccessible) by CPU, so that we can
  * migrate part of a process memory to device memory.
  *