linux.git/mm/Kconfig, branch v5.17

mm: hide the FRONTSWAP Kconfig symbol

2022-01-22T06:33:38+00:00

Select FRONTSWAP from ZSWAP instead of prompting for it.

Link: https://lkml.kernel.org/r/20211224062246.1258487-14-hch@lst.de
Signed-off-by: Christoph Hellwig 
Reviewed-by: Juergen Gross 
Cc: Dan Streetman 
Cc: Geert Uytterhoeven 
Cc: Hugh Dickins 
Cc: Konrad Rzeszutek Wilk 
Cc: Matthew Wilcox (Oracle) 
Cc: Seth Jennings 
Cc: Vitaly Wool 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: remove cleancache

2022-01-22T06:33:38+00:00

Patch series "remove Xen tmem leftovers".

Since the removal of the Xen tmem driver in 2019, the cleancache hooks
are entirely unused, as are large parts of frontswap.  This series
against linux-next (with the folio changes included) removes
cleancaches, and cuts down frontswap to the bits actually used by zswap.

This patch (of 13):

The cleancache subsystem is unused since the removal of Xen tmem driver
in commit 814bbf49dcd0 ("xen: remove tmem driver").

[akpm@linux-foundation.org: remove now-unreachable code]

Link: https://lkml.kernel.org/r/20211224062246.1258487-1-hch@lst.de
Link: https://lkml.kernel.org/r/20211224062246.1258487-2-hch@lst.de
Signed-off-by: Christoph Hellwig 
Reviewed-by: Juergen Gross 
Acked-by: Geert Uytterhoeven 
Cc: Konrad Rzeszutek Wilk 
Cc: Hugh Dickins 
Cc: Seth Jennings 
Cc: Dan Streetman 
Cc: Vitaly Wool 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2022-01-20T08:41:01+00:00

Merge more updates from Andrew Morton:
 "55 patches.

  Subsystems affected by this patch series: percpu, procfs, sysctl,
  misc, core-kernel, get_maintainer, lib, checkpatch, binfmt, nilfs2,
  hfs, fat, adfs, panic, delayacct, kconfig, kcov, and ubsan"

* emailed patches from Andrew Morton : (55 commits)
  lib: remove redundant assignment to variable ret
  ubsan: remove CONFIG_UBSAN_OBJECT_SIZE
  kcov: fix generic Kconfig dependencies if ARCH_WANTS_NO_INSTR
  lib/Kconfig.debug: make TEST_KMOD depend on PAGE_SIZE_LESS_THAN_256KB
  btrfs: use generic Kconfig option for 256kB page size limit
  arch/Kconfig: split PAGE_SIZE_LESS_THAN_256KB from PAGE_SIZE_LESS_THAN_64KB
  configs: introduce debug.config for CI-like setup
  delayacct: track delays from memory compact
  Documentation/accounting/delay-accounting.rst: add thrashing page cache and direct compact
  delayacct: cleanup flags in struct task_delay_info and functions use it
  delayacct: fix incomplete disable operation when switch enable to disable
  delayacct: support swapin delay accounting for swapping without blkio
  panic: remove oops_id
  panic: use error_report_end tracepoint on warnings
  fs/adfs: remove unneeded variable make code cleaner
  FAT: use io_schedule_timeout() instead of congestion_wait()
  hfsplus: use struct_group_attr() for memcpy() region
  nilfs2: remove redundant pointer sbufs
  fs/binfmt_elf: use PT_LOAD p_align values for static PIE
  const_structs.checkpatch: add frequently used ops structs
  ...

mm: percpu: generalize percpu related config

2022-01-20T06:52:52+00:00

Patch series "mm: percpu: Cleanup percpu first chunk function".

When supporting page mapping percpu first chunk allocator on arm64, we
found there are lots of duplicated codes in percpu embed/page first chunk
allocator.  This patchset is aimed to cleanup them and should no function
change.

The currently supported status about 'embed' and 'page' in Archs shows
below,

	embed: NEED_PER_CPU_PAGE_FIRST_CHUNK
	page:  NEED_PER_CPU_EMBED_FIRST_CHUNK

		embed	page
	------------------------
	arm64	  Y	 Y
	mips	  Y	 N
	powerpc	  Y	 Y
	riscv	  Y	 N
	sparc	  Y	 Y
	x86	  Y	 Y
	------------------------

There are two interfaces about percpu first chunk allocator,

 extern int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
                                size_t atom_size,
                                pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
-                               pcpu_fc_alloc_fn_t alloc_fn,
-                               pcpu_fc_free_fn_t free_fn);
+                               pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn);

 extern int __init pcpu_page_first_chunk(size_t reserved_size,
-                               pcpu_fc_alloc_fn_t alloc_fn,
-                               pcpu_fc_free_fn_t free_fn,
-                               pcpu_fc_populate_pte_fn_t populate_pte_fn);
+                               pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn);

The pcpu_fc_alloc_fn_t/pcpu_fc_free_fn_t is killed, we provide generic
pcpu_fc_alloc() and pcpu_fc_free() function, which are called in the
pcpu_embed/page_first_chunk().

1) For pcpu_embed_first_chunk(), pcpu_fc_cpu_to_node_fn_t is needed to be
   provided when archs supported NUMA.

2) For pcpu_page_first_chunk(), the pcpu_fc_populate_pte_fn_t is killed too,
   a generic pcpu_populate_pte() which marked '__weak' is provided, if you
   need a different function to populate pte on the arch(like x86), please
   provide its own implementation.

[1] https://github.com/kevin78/linux.git percpu-cleanup

This patch (of 4):

The HAVE_SETUP_PER_CPU_AREA/NEED_PER_CPU_EMBED_FIRST_CHUNK/
NEED_PER_CPU_PAGE_FIRST_CHUNK/USE_PERCPU_NUMA_NODE_ID configs, which have
duplicate definitions on platforms that subscribe it.

Move them into mm, drop these redundant definitions and instead just
select it on applicable platforms.

Link: https://lkml.kernel.org/r/20211216112359.103822-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20211216112359.103822-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang 
Acked-by: Catalin Marinas 	[arm64]
Cc: Will Deacon 
Cc: Thomas Bogendoerfer 
Cc: Michael Ellerman 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Paul Walmsley 
Cc: Palmer Dabbelt 
Cc: Albert Ou 
Cc: "David S. Miller" 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: "H. Peter Anvin" 
Cc: Christoph Lameter 
Cc: Dennis Zhou 
Cc: Greg Kroah-Hartman 
Cc: "Rafael J. Wysocki" 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: add a field to store names for private anonymous memory

2022-01-15T14:30:27+00:00

In many userspace applications, and especially in VM based applications
like Android uses heavily, there are multiple different allocators in
use.  At a minimum there is libc malloc and the stack, and in many cases
there are libc malloc, the stack, direct syscalls to mmap anonymous
memory, and multiple VM heaps (one for small objects, one for big
objects, etc.).  Each of these layers usually has its own tools to
inspect its usage; malloc by compiling a debug version, the VM through
heap inspection tools, and for direct syscalls there is usually no way
to track them.

On Android we heavily use a set of tools that use an extended version of
the logic covered in Documentation/vm/pagemap.txt to walk all pages
mapped in userspace and slice their usage by process, shared (COW) vs.
unique mappings, backing, etc.  This can account for real physical
memory usage even in cases like fork without exec (which Android uses
heavily to share as many private COW pages as possible between
processes), Kernel SamePage Merging, and clean zero pages.  It produces
a measurement of the pages that only exist in that process (USS, for
unique), and a measurement of the physical memory usage of that process
with the cost of shared pages being evenly split between processes that
share them (PSS).

If all anonymous memory is indistinguishable then figuring out the real
physical memory usage (PSS) of each heap requires either a pagemap
walking tool that can understand the heap debugging of every layer, or
for every layer's heap debugging tools to implement the pagemap walking
logic, in which case it is hard to get a consistent view of memory
across the whole system.

Tracking the information in userspace leads to all sorts of problems.
It either needs to be stored inside the process, which means every
process has to have an API to export its current heap information upon
request, or it has to be stored externally in a filesystem that somebody
needs to clean up on crashes.  It needs to be readable while the process
is still running, so it has to have some sort of synchronization with
every layer of userspace.  Efficiently tracking the ranges requires
reimplementing something like the kernel vma trees, and linking to it
from every layer of userspace.  It requires more memory, more syscalls,
more runtime cost, and more complexity to separately track regions that
the kernel is already tracking.

This patch adds a field to /proc/pid/maps and /proc/pid/smaps to show a
userspace-provided name for anonymous vmas.  The names of named
anonymous vmas are shown in /proc/pid/maps and /proc/pid/smaps as
[anon:].

Userspace can set the name for a region of memory by calling

   prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, (unsigned long)name)

Setting the name to NULL clears it.  The name length limit is 80 bytes
including NUL-terminator and is checked to contain only printable ascii
characters (including space), except '[',']','\','$' and '`'.

Ascii strings are being used to have a descriptive identifiers for vmas,
which can be understood by the users reading /proc/pid/maps or
/proc/pid/smaps.  Names can be standardized for a given system and they
can include some variable parts such as the name of the allocator or a
library, tid of the thread using it, etc.

The name is stored in a pointer in the shared union in vm_area_struct
that points to a null terminated string.  Anonymous vmas with the same
name (equivalent strings) and are otherwise mergeable will be merged.
The name pointers are not shared between vmas even if they contain the
same name.  The name pointer is stored in a union with fields that are
only used on file-backed mappings, so it does not increase memory usage.

CONFIG_ANON_VMA_NAME kernel configuration is introduced to enable this
feature.  It keeps the feature disabled by default to prevent any
additional memory overhead and to avoid confusing procfs parsers on
systems which are not ready to support named anonymous vmas.

The patch is based on the original patch developed by Colin Cross, more
specifically on its latest version [1] posted upstream by Sumit Semwal.
It used a userspace pointer to store vma names.  In that design, name
pointers could be shared between vmas.  However during the last
upstreaming attempt, Kees Cook raised concerns [2] about this approach
and suggested to copy the name into kernel memory space, perform
validity checks [3] and store as a string referenced from
vm_area_struct.

One big concern is about fork() performance which would need to strdup
anonymous vma names.  Dave Hansen suggested experimenting with
worst-case scenario of forking a process with 64k vmas having longest
possible names [4].  I ran this experiment on an ARM64 Android device
and recorded a worst-case regression of almost 40% when forking such a
process.

This regression is addressed in the followup patch which replaces the
pointer to a name with a refcounted structure that allows sharing the
name pointer between vmas of the same name.  Instead of duplicating the
string during fork() or when splitting a vma it increments the refcount.

[1] https://lore.kernel.org/linux-mm/20200901161459.11772-4-sumit.semwal@linaro.org/
[2] https://lore.kernel.org/linux-mm/202009031031.D32EF57ED@keescook/
[3] https://lore.kernel.org/linux-mm/202009031022.3834F692@keescook/
[4] https://lore.kernel.org/linux-mm/5d0358ab-8c47-2f5f-8e43-23b89d6a8e95@intel.com/

Changes for prctl(2) manual page (in the options section):

PR_SET_VMA
	Sets an attribute specified in arg2 for virtual memory areas
	starting from the address specified in arg3 and spanning the
	size specified	in arg4. arg5 specifies the value of the attribute
	to be set. Note that assigning an attribute to a virtual memory
	area might prevent it from being merged with adjacent virtual
	memory areas due to the difference in that attribute's value.

	Currently, arg2 must be one of:

	PR_SET_VMA_ANON_NAME
		Set a name for anonymous virtual memory areas. arg5 should
		be a pointer to a null-terminated string containing the
		name. The name length including null byte cannot exceed
		80 bytes. If arg5 is NULL, the name of the appropriate
		anonymous virtual memory areas will be reset. The name
		can contain only printable ascii characters (including
                space), except '[',']','\','$' and '`'.

                This feature is available only if the kernel is built with
                the CONFIG_ANON_VMA_NAME option enabled.

[surenb@google.com: docs: proc.rst: /proc/PID/maps: fix malformed table]
  Link: https://lkml.kernel.org/r/20211123185928.2513763-1-surenb@google.com
[surenb: rebased over v5.15-rc6, replaced userpointer with a kernel copy,
 added input sanitization and CONFIG_ANON_VMA_NAME config. The bulk of the
 work here was done by Colin Cross, therefore, with his permission, keeping
 him as the author]

Link: https://lkml.kernel.org/r/20211019215511.3771969-2-surenb@google.com
Signed-off-by: Colin Cross 
Signed-off-by: Suren Baghdasaryan 
Reviewed-by: Kees Cook 
Cc: Stephen Rothwell 
Cc: Al Viro 
Cc: Cyrill Gorcunov 
Cc: Dave Hansen 
Cc: David Rientjes 
Cc: "Eric W. Biederman" 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: Jan Glauber 
Cc: Johannes Weiner 
Cc: John Stultz 
Cc: Mel Gorman 
Cc: Minchan Kim 
Cc: Oleg Nesterov 
Cc: Pekka Enberg 
Cc: Peter Zijlstra 
Cc: Rob Landley 
Cc: "Serge E. Hallyn" 
Cc: Shaohua Li 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

percpu: km: ensure it is used with NOMMU (either UP or SMP)

2021-12-06T17:45:09+00:00

Currently, NOMMU pull km allocator via !SMP dependency because most of
them are UP, yet for SMP+NOMMU vm allocator gets pulled which:

* may lead to broken build [1]
* ...or not working runtime due to [2]

It looks like SMP+NOMMU case was overlooked in bbddff054587 ("percpu:
use percpu allocator on UP too") so restore that.

[1]
For ARM SMP+NOMMU (R-class cores)

arm-none-linux-gnueabihf-ld: mm/percpu.o: in function `pcpu_post_unmap_tlb_flush':
mm/percpu-vm.c:188: undefined reference to `flush_tlb_kernel_range'

[2]
static inline
int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
                pgprot_t prot, struct page **pages, unsigned int page_shift)
{
       return -EINVAL;
}

Signed-off-by: Vladimir Murzin 
Tested-by: Rob Landley 
Tested-by: Rich Felker 
[Dennis: use depends instead of default for condition]
Signed-off-by: Dennis Zhou

kmap_local: don't assume kmap PTEs are linear arrays in memory

2021-11-20T18:35:54+00:00

The kmap_local conversion broke the ARM architecture, because the new
code assumes that all PTEs used for creating kmaps form a linear array
in memory, and uses array indexing to look up the kmap PTE belonging to
a certain kmap index.

On ARM, this cannot work, not only because the PTE pages may be
non-adjacent in memory, but also because ARM/!LPAE interleaves hardware
entries and extended entries (carrying software-only bits) in a way that
is not compatible with array indexing.

Fortunately, this only seems to affect configurations with more than 8
CPUs, due to the way the per-CPU kmap slots are organized in memory.

Work around this by permitting an architecture to set a Kconfig symbol
that signifies that the kmap PTEs do not form a lineary array in memory,
and so the only way to locate the appropriate one is to walk the page
tables.

Link: https://lore.kernel.org/linux-arm-kernel/20211026131249.3731275-1-ardb@kernel.org/
Link: https://lkml.kernel.org/r/20211116094737.7391-1-ardb@kernel.org
Fixes: 2a15ba82fa6c ("ARM: highmem: Switch to generic kmap atomic")
Signed-off-by: Ard Biesheuvel 
Reported-by: Quanyang Wang 
Reviewed-by: Linus Walleij 
Acked-by: Russell King (Oracle) 
Cc: Thomas Gleixner 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel/resource: disallow access to exclusive system RAM regions

2021-11-09T18:02:52+00:00

virtio-mem dynamically exposes memory inside a device memory region as
system RAM to Linux, coordinating with the hypervisor which parts are
actually "plugged" and consequently usable/accessible.

On the one hand, the virtio-mem driver adds/removes whole memory blocks,
creating/removing busy IORESOURCE_SYSTEM_RAM resources, on the other
hand, it logically (un)plugs memory inside added memory blocks,
dynamically either exposing them to the buddy or hiding them from the
buddy and marking them PG_offline.

In contrast to physical devices, like a DIMM, the virtio-mem driver is
required to actually make use of any of the device-provided memory,
because it performs the handshake with the hypervisor.  virtio-mem
memory cannot simply be access via /dev/mem without a driver.

There is no safe way to:
a) Access plugged memory blocks via /dev/mem, as they might contain
   unplugged holes or might get silently unplugged by the virtio-mem
   driver and consequently turned inaccessible.
b) Access unplugged memory blocks via /dev/mem because the virtio-mem
   driver is required to make them actually accessible first.

The virtio-spec states that unplugged memory blocks MUST NOT be written,
and only selected unplugged memory blocks MAY be read.  We want to make
sure, this is the case in sane environments -- where the virtio-mem driver
was loaded.

We want to make sure that in a sane environment, nobody "accidentially"
accesses unplugged memory inside the device managed region.  For example,
a user might spot a memory region in /proc/iomem and try accessing it via
/dev/mem via gdb or dumping it via something else.  By the time the mmap()
happens, the memory might already have been removed by the virtio-mem
driver silently: the mmap() would succeeed and user space might
accidentially access unplugged memory.

So once the driver was loaded and detected the device along the
device-managed region, we just want to disallow any access via /dev/mem to
it.

In an ideal world, we would mark the whole region as busy ("owned by a
driver") and exclude it; however, that would be wrong, as we don't really
have actual system RAM at these ranges added to Linux ("busy system RAM").
Instead, we want to mark such ranges as "not actual busy system RAM but
still soft-reserved and prepared by a driver for future use."

Let's teach iomem_is_exclusive() to reject access to any range with
"IORESOURCE_SYSTEM_RAM | IORESOURCE_EXCLUSIVE", even if not busy and even
if "iomem=relaxed" is set.  Introduce EXCLUSIVE_SYSTEM_RAM to make it
easier for applicable drivers to depend on this setting in their Kconfig.

For now, there are no applicable ranges and we'll modify virtio-mem next
to properly set IORESOURCE_EXCLUSIVE on the parent resource container it
creates to contain all actual busy system RAM added via
add_memory_driver_managed().

Link: https://lkml.kernel.org/r/20210920142856.17758-3-david@redhat.com
Signed-off-by: David Hildenbrand 
Reviewed-by: Dan Williams 
Cc: Andy Shevchenko 
Cc: Arnd Bergmann 
Cc: Greg Kroah-Hartman 
Cc: Hanjun Guo 
Cc: Jason Wang 
Cc: "Michael S. Tsirkin" 
Cc: "Rafael J. Wysocki" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/memory_hotplug: restrict CONFIG_MEMORY_HOTPLUG to 64 bit

2021-11-06T20:30:42+00:00

32 bit support is broken in various ways: for example, we can online
memory that should actually go to ZONE_HIGHMEM to ZONE_MOVABLE or in
some cases even to one of the other kernel zones.

We marked it BROKEN in commit b59d02ed0869 ("mm/memory_hotplug: disable
the functionality for 32b") almost one year ago.  According to that
commit it might be broken at least since 2017.  Further, there is hardly
a sane use case nowadays.

Let's just depend completely on 64bit, dropping the "BROKEN" dependency
to make clear that we are not going to support it again.  Next, we'll
remove some HIGHMEM leftovers from memory hotplug code to clean up.

Link: https://lkml.kernel.org/r/20210929143600.49379-4-david@redhat.com
Signed-off-by: David Hildenbrand 
Reviewed-by: Oscar Salvador 
Cc: Alex Shi 
Cc: Andy Lutomirski 
Cc: Benjamin Herrenschmidt 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: Greg Kroah-Hartman 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Jason Wang 
Cc: Jonathan Corbet 
Cc: Michael Ellerman 
Cc: "Michael S. Tsirkin" 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: "Rafael J. Wysocki" 
Cc: Shuah Khan 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/memory_hotplug: remove CONFIG_MEMORY_HOTPLUG_SPARSE

2021-11-06T20:30:42+00:00

CONFIG_MEMORY_HOTPLUG depends on CONFIG_SPARSEMEM, so there is no need for
CONFIG_MEMORY_HOTPLUG_SPARSE anymore; adjust all instances to use
CONFIG_MEMORY_HOTPLUG and remove CONFIG_MEMORY_HOTPLUG_SPARSE.

Link: https://lkml.kernel.org/r/20210929143600.49379-3-david@redhat.com
Signed-off-by: David Hildenbrand 
Acked-by: Shuah Khan 	[kselftest]
Acked-by: Greg Kroah-Hartman 
Acked-by: Oscar Salvador 
Cc: Alex Shi 
Cc: Andy Lutomirski 
Cc: Benjamin Herrenschmidt 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Jason Wang 
Cc: Jonathan Corbet 
Cc: Michael Ellerman 
Cc: "Michael S. Tsirkin" 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: "Rafael J. Wysocki" 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds