Merge tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
   switching from a user process to a kernel thread.

 - More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
   Raghav.

 - zsmalloc performance improvements from Sergey Senozhatsky.

 - Yue Zhao has found and fixed some data race issues around the
   alteration of memcg userspace tunables.

 - VFS rationalizations from Christoph Hellwig:
     - removal of most of the callers of write_one_page()
     - make __filemap_get_folio()'s return value more useful

 - Luis Chamberlain has changed tmpfs so it no longer requires swap
   backing. Use `mount -o noswap'.

 - Qi Zheng has made the slab shrinkers operate locklessly, providing
   some scalability benefits.

 - Keith Busch has improved dmapool's performance, making part of its
   operations O(1) rather than O(n).

 - Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
   permitting userspace to wr-protect anon memory unpopulated ptes.

 - Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
   rather than exclusive, and has fixed a bunch of errors which were
   caused by its unintuitive meaning.

 - Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
   which causes minor faults to install a write-protected pte.

 - Vlastimil Babka has done some maintenance work on vma_merge():
   cleanups to the kernel code and improvements to our userspace test
   harness.

 - Cleanups to do_fault_around() by Lorenzo Stoakes.

 - Mike Rapoport has moved a lot of initialization code out of various
   mm/ files and into mm/mm_init.c.

 - Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
   DRM, but DRM doesn't use it any more.

 - Lorenzo has also coverted read_kcore() and vread() to use iterators
   and has thereby removed the use of bounce buffers in some cases.

 - Lorenzo has also contributed further cleanups of vma_merge().

 - Chaitanya Prakash provides some fixes to the mmap selftesting code.

 - Matthew Wilcox changes xfs and afs so they no longer take sleeping
   locks in ->map_page(), a step towards RCUification of pagefaults.

 - Suren Baghdasaryan has improved mmap_lock scalability by switching to
   per-VMA locking.

 - Frederic Weisbecker has reworked the percpu cache draining so that it
   no longer causes latency glitches on cpu isolated workloads.

 - Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
   logic.

 - Liu Shixin has changed zswap's initialization so we no longer waste a
   chunk of memory if zswap is not being used.

 - Yosry Ahmed has improved the performance of memcg statistics
   flushing.

 - David Stevens has fixed several issues involving khugepaged,
   userfaultfd and shmem.

 - Christoph Hellwig has provided some cleanup work to zram's IO-related
   code paths.

 - David Hildenbrand has fixed up some issues in the selftest code's
   testing of our pte state changing.

 - Pankaj Raghav has made page_endio() unneeded and has removed it.

 - Peter Xu contributed some rationalizations of the userfaultfd
   selftests.

 - Yosry Ahmed has fixed an issue around memcg's page recalim
   accounting.

 - Chaitanya Prakash has fixed some arm-related issues in the
   selftests/mm code.

 - Longlong Xia has improved the way in which KSM handles hwpoisoned
   pages.

 - Peter Xu fixes a few issues with uffd-wp at fork() time.

 - Stefan Roesch has changed KSM so that it may now be used on a
   per-process and per-cgroup basis.

* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
  mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
  shmem: restrict noswap option to initial user namespace
  mm/khugepaged: fix conflicting mods to collapse_file()
  sparse: remove unnecessary 0 values from rc
  mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
  hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
  maple_tree: fix allocation in mas_sparse_area()
  mm: do not increment pgfault stats when page fault handler retries
  zsmalloc: allow only one active pool compaction context
  selftests/mm: add new selftests for KSM
  mm: add new KSM process and sysfs knobs
  mm: add new api to enable ksm per process
  mm: shrinkers: fix debugfs file permissions
  mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
  migrate_pages_batch: fix statistics for longterm pin retry
  userfaultfd: use helper function range_in_vma()
  lib/show_mem.c: use for_each_populated_zone() simplify code
  mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
  fs/buffer: convert create_page_buffers to folio_create_buffers
  fs/buffer: add folio_create_empty_buffers helper
  ...

Documentation/filesystems/locking.rst

@@ -645,7 +645,7 @@ ops		mmap_lock	PageLocked(page)
 open:		yes
 close:		yes
 fault:		yes		can return with page locked
-map_pages:	yes
+map_pages:	read
 page_mkwrite:	yes		can return with page locked
 pfn_mkwrite:	yes
 access:		yes
@@ -661,7 +661,7 @@ locked. The VM will unlock the page.
 
 ->map_pages() is called when VM asks to map easy accessible pages.
 Filesystem should find and map pages associated with offsets from "start_pgoff"
-till "end_pgoff". ->map_pages() is called with page table locked and must
+till "end_pgoff". ->map_pages() is called with the RCU lock held and must
 not block.  If it's not possible to reach a page without blocking,
 filesystem should skip it. Filesystem should use do_set_pte() to setup
 page table entry. Pointer to entry associated with the page is passed in

Documentation/filesystems/proc.rst

@@ -996,6 +996,7 @@ Example output. You may not have all of these fields.
     VmallocUsed:       40444 kB
     VmallocChunk:          0 kB
     Percpu:            29312 kB
+    EarlyMemtestBad:       0 kB
     HardwareCorrupted:     0 kB
     AnonHugePages:   4149248 kB
     ShmemHugePages:        0 kB
@@ -1146,6 +1147,13 @@ VmallocChunk
 Percpu
               Memory allocated to the percpu allocator used to back percpu
               allocations. This stat excludes the cost of metadata.
+EarlyMemtestBad
+              The amount of RAM/memory in kB, that was identified as corrupted
+              by early memtest. If memtest was not run, this field will not
+              be displayed at all. Size is never rounded down to 0 kB.
+              That means if 0 kB is reported, you can safely assume
+              there was at least one pass of memtest and none of the passes
+              found a single faulty byte of RAM.
 HardwareCorrupted
               The amount of RAM/memory in KB, the kernel identifies as
               corrupted.

Documentation/filesystems/tmpfs.rst

@@ -13,17 +13,29 @@ everything stored therein is lost.
 
 tmpfs puts everything into the kernel internal caches and grows and
 shrinks to accommodate the files it contains and is able to swap
-unneeded pages out to swap space. It has maximum size limits which can
-be adjusted on the fly via 'mount -o remount ...'
+unneeded pages out to swap space, if swap was enabled for the tmpfs
+mount. tmpfs also supports THP.
 
-If you compare it to ramfs (which was the template to create tmpfs)
-you gain swapping and limit checking. Another similar thing is the RAM
-disk (/dev/ram*), which simulates a fixed size hard disk in physical
-RAM, where you have to create an ordinary filesystem on top. Ramdisks
-cannot swap and you do not have the possibility to resize them.
+tmpfs extends ramfs with a few userspace configurable options listed and
+explained further below, some of which can be reconfigured dynamically on the
+fly using a remount ('mount -o remount ...') of the filesystem. A tmpfs
+filesystem can be resized but it cannot be resized to a size below its current
+usage. tmpfs also supports POSIX ACLs, and extended attributes for the
+trusted.* and security.* namespaces. ramfs does not use swap and you cannot
+modify any parameter for a ramfs filesystem. The size limit of a ramfs
+filesystem is how much memory you have available, and so care must be taken if
+used so to not run out of memory.
 
-Since tmpfs lives completely in the page cache and on swap, all tmpfs
-pages will be shown as "Shmem" in /proc/meminfo and "Shared" in
+An alternative to tmpfs and ramfs is to use brd to create RAM disks
+(/dev/ram*), which allows you to simulate a block device disk in physical RAM.
+To write data you would just then need to create an regular filesystem on top
+this ramdisk. As with ramfs, brd ramdisks cannot swap. brd ramdisks are also
+configured in size at initialization and you cannot dynamically resize them.
+Contrary to brd ramdisks, tmpfs has its own filesystem, it does not rely on the
+block layer at all.
+
+Since tmpfs lives completely in the page cache and optionally on swap,
+all tmpfs pages will be shown as "Shmem" in /proc/meminfo and "Shared" in
 free(1). Notice that these counters also include shared memory
 (shmem, see ipcs(1)). The most reliable way to get the count is
 using df(1) and du(1).
@@ -72,6 +84,8 @@ nr_inodes  The maximum number of inodes for this instance. The default
            is half of the number of your physical RAM pages, or (on a
            machine with highmem) the number of lowmem RAM pages,
            whichever is the lower.
+noswap     Disables swap. Remounts must respect the original settings.
+           By default swap is enabled.
 =========  ============================================================
 
 These parameters accept a suffix k, m or g for kilo, mega and giga and
@@ -85,6 +99,36 @@ mount with such options, since it allows any user with write access to
 use up all the memory on the machine; but enhances the scalability of
 that instance in a system with many CPUs making intensive use of it.
 
+tmpfs also supports Transparent Huge Pages which requires a kernel
+configured with CONFIG_TRANSPARENT_HUGEPAGE and with huge supported for
+your system (has_transparent_hugepage(), which is architecture specific).
+The mount options for this are:
+
+======  ============================================================
+huge=0  never: disables huge pages for the mount
+huge=1  always: enables huge pages for the mount
+huge=2  within_size: only allocate huge pages if the page will be
+        fully within i_size, also respect fadvise()/madvise() hints.
+huge=3  advise: only allocate huge pages if requested with
+        fadvise()/madvise()
+======  ============================================================
+
+There is a sysfs file which you can also use to control system wide THP
+configuration for all tmpfs mounts, the file is:
+
+/sys/kernel/mm/transparent_hugepage/shmem_enabled
+
+This sysfs file is placed on top of THP sysfs directory and so is registered
+by THP code. It is however only used to control all tmpfs mounts with one
+single knob. Since it controls all tmpfs mounts it should only be used either
+for emergency or testing purposes. The values you can set for shmem_enabled are:
+
+==  ============================================================
+-1  deny: disables huge on shm_mnt and all mounts, for
+    emergency use
+-2  force: enables huge on shm_mnt and all mounts, w/o needing
+    option, for testing
+==  ============================================================
 
 tmpfs has a mount option to set the NUMA memory allocation policy for
 all files in that instance (if CONFIG_NUMA is enabled) - which can be