Merge branch 'akpm' (patches from Andrew)

Merge yet more updates from Andrew Morton:
 "This is the post-linux-next queue. Material which was based on or
  dependent upon material which was in -next.

  69 patches.

  Subsystems affected by this patch series: mm (migration and zsmalloc),
  sysctl, proc, and lib"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (69 commits)
  mm: hide the FRONTSWAP Kconfig symbol
  frontswap: remove support for multiple ops
  mm: mark swap_lock and swap_active_head static
  frontswap: simplify frontswap_register_ops
  frontswap: remove frontswap_test
  mm: simplify try_to_unuse
  frontswap: remove the frontswap exports
  frontswap: simplify frontswap_init
  frontswap: remove frontswap_curr_pages
  frontswap: remove frontswap_shrink
  frontswap: remove frontswap_tmem_exclusive_gets
  frontswap: remove frontswap_writethrough
  mm: remove cleancache
  lib/stackdepot: always do filter_irq_stacks() in stack_depot_save()
  lib/stackdepot: allow optional init and stack_table allocation by kvmalloc()
  proc: remove PDE_DATA() completely
  fs: proc: store PDE()->data into inode->i_private
  zsmalloc: replace get_cpu_var with local_lock
  zsmalloc: replace per zpage lock with pool->migrate_lock
  locking/rwlocks: introduce write_lock_nested
  ...

Author: torvalds

Documentation/vm/cleancache.rst

@@ -8,12 +8,6 @@ Frontswap provides a "transcendent memory" interface for swap pages.
 In some environments, dramatic performance savings may be obtained because
 swapped pages are saved in RAM (or a RAM-like device) instead of a swap disk.
 
-(Note, frontswap -- and :ref:`cleancache` (merged at 3.0) -- are the "frontends"
-and the only necessary changes to the core kernel for transcendent memory;
-all other supporting code -- the "backends" -- is implemented as drivers.
-See the LWN.net article `Transcendent memory in a nutshell`_
-for a detailed overview of frontswap and related kernel parts)
-
 .. _Transcendent memory in a nutshell: https://lwn.net/Articles/454795/
 
 Frontswap is so named because it can be thought of as the opposite of
@@ -45,12 +39,6 @@ a disk write and, if the data is later read back, a disk read are avoided.
 If a store returns failure, transcendent memory has rejected the data, and the
 page can be written to swap as usual.
 
-If a backend chooses, frontswap can be configured as a "writethrough
-cache" by calling frontswap_writethrough().  In this mode, the reduction
-in swap device writes is lost (and also a non-trivial performance advantage)
-in order to allow the backend to arbitrarily "reclaim" space used to
-store frontswap pages to more completely manage its memory usage.
-
 Note that if a page is stored and the page already exists in transcendent memory
 (a "duplicate" store), either the store succeeds and the data is overwritten,
 or the store fails AND the page is invalidated.  This ensures stale data may
@@ -87,11 +75,9 @@ This interface is ideal when data is transformed to a different form
 and size (such as with compression) or secretly moved (as might be
 useful for write-balancing for some RAM-like devices).  Swap pages (and
 evicted page-cache pages) are a great use for this kind of slower-than-RAM-
-but-much-faster-than-disk "pseudo-RAM device" and the frontswap (and
-cleancache) interface to transcendent memory provides a nice way to read
-and write -- and indirectly "name" -- the pages.
+but-much-faster-than-disk "pseudo-RAM device".
 
-Frontswap -- and cleancache -- with a fairly small impact on the kernel,
+Frontswap with a fairly small impact on the kernel,
 provides a huge amount of flexibility for more dynamic, flexible RAM
 utilization in various system configurations:
 
@@ -269,19 +255,6 @@ the old data and ensure that it is no longer accessible.  Since the
 swap subsystem then writes the new data to the read swap device,
 this is the correct course of action to ensure coherency.
 
-* What is frontswap_shrink for?
-
-When the (non-frontswap) swap subsystem swaps out a page to a real
-swap device, that page is only taking up low-value pre-allocated disk
-space.  But if frontswap has placed a page in transcendent memory, that
-page may be taking up valuable real estate.  The frontswap_shrink
-routine allows code outside of the swap subsystem to force pages out
-of the memory managed by frontswap and back into kernel-addressable memory.
-For example, in RAMster, a "suction driver" thread will attempt
-to "repatriate" pages sent to a remote machine back to the local machine;
-this is driven using the frontswap_shrink mechanism when memory pressure
-subsides.
-
 * Why does the frontswap patch create the new include file swapfile.h?
 
 The frontswap code depends on some swap-subsystem-internal data

Documentation/vm/frontswap.rst

@@ -15,7 +15,6 @@ algorithms.  If you are looking for advice on simply allocating memory, see the
    active_mm
    arch_pgtable_helpers
    balance
-   cleancache
    damon/index
    free_page_reporting
    frontswap

Documentation/vm/index.rst

@@ -4705,13 +4705,6 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/cla
 F:	include/linux/cfi.h
 F:	kernel/cfi.c
 
-CLEANCACHE API
-M:	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
-L:	linux-kernel@vger.kernel.org
-S:	Maintained
-F:	include/linux/cleancache.h
-F:	mm/cleancache.c
-
 CLK API
 M:	Russell King <linux@armlinux.org.uk>
 L:	linux-clk@vger.kernel.org

MAINTAINERS

@@ -83,14 +83,14 @@ static int srm_env_proc_show(struct seq_file *m, void *v)
 
 static int srm_env_proc_open(struct inode *inode, struct file *file)
 {
-	return single_open(file, srm_env_proc_show, PDE_DATA(inode));
+	return single_open(file, srm_env_proc_show, pde_data(inode));
 }
 
 static ssize_t srm_env_proc_write(struct file *file, const char __user *buffer,
 				  size_t count, loff_t *pos)
 {
 	int res;
-	unsigned long	id = (unsigned long)PDE_DATA(file_inode(file));
+	unsigned long	id = (unsigned long)pde_data(file_inode(file));
 	char		*buf = (char *) __get_free_page(GFP_USER);
 	unsigned long	ret1, ret2;