linux.git/mm/mm_init.c, branch v6.10

Revert "mm: init_mlocked_on_free_v3"

2024-06-15T17:43:05+00:00

There was insufficient review and no agreement that this is the right
approach.

There are serious flaws with the implementation that make processes using
mlock() not even work with simple fork() [1] and we get reliable crashes
when rebooting.

Further, simply because we might be unmapping a single PTE of a large
mlocked folio, we shouldn't zero out the whole folio.

... especially because the code can also *corrupt* urelated memory because
	kernel_init_pages(page, folio_nr_pages(folio));

Could end up writing outside of the actual folio if we work with a tail
page.

Let's revert it.  Once there is agreement that this is the right approach,
the issues were fixed and there was reasonable review and proper testing,
we can consider it again.

[1] https://lkml.kernel.org/r/4da9da2f-73e4-45fd-b62f-a8a513314057@redhat.com

Link: https://lkml.kernel.org/r/20240605091710.38961-1-david@redhat.com
Fixes: ba42b524a040 ("mm: init_mlocked_on_free_v3")
Signed-off-by: David Hildenbrand 
Reported-by: David Wang <00107082@163.com>
Closes: https://lore.kernel.org/lkml/20240528151340.4282-1-00107082@163.com/
Reported-by: Lance Yang 
Closes: https://lkml.kernel.org/r/20240601140917.43562-1-ioworker0@gmail.com
Acked-by: Lance Yang 
Cc: York Jasper Niebuhr 
Cc: Matthew Wilcox (Oracle) 
Cc: Kees Cook 
Signed-off-by: Andrew Morton

Merge tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-05-19T16:21:03+00:00

Pull mm updates from Andrew Morton:
"The usual shower of singleton fixes and minor series all over MM,
documented (hopefully adequately) in the respective changelogs.
Notable series include:

- Lucas Stach has provided some page-mapping cleanup/consolidation/
maintainability work in the series "mm/treewide: Remove pXd_huge()
API".

- In the series "Allow migrate on protnone reference with
MPOL_PREFERRED_MANY policy", Donet Tom has optimized mempolicy's
MPOL_PREFERRED_MANY mode, yielding almost doubled performance in
one test.

- In their series "Memory allocation profiling" Kent Overstreet and
Suren Baghdasaryan have contributed a means of determining (via
/proc/allocinfo) whereabouts in the kernel memory is being
allocated: number of calls and amount of memory.

- Matthew Wilcox has provided the series "Various significant MM
patches" which does a number of rather unrelated things, but in
largely similar code sites.

- In his series "mm: page_alloc: freelist migratetype hygiene"
Johannes Weiner has fixed the page allocator's handling of
migratetype requests, with resulting improvements in compaction
efficiency.

- In the series "make the hugetlb migration strategy consistent"
Baolin Wang has fixed a hugetlb migration issue, which should
improve hugetlb allocation reliability.

- Liu Shixin has hit an I/O meltdown caused by readahead in a
memory-tight memcg. Addressed in the series "Fix I/O high when
memory almost met memcg limit".

- In the series "mm/filemap: optimize folio adding and splitting"
Kairui Song has optimized pagecache insertion, yielding ~10%
performance improvement in one test.

- Baoquan He has cleaned up and consolidated the early zone
initialization code in the series "mm/mm_init.c: refactor
free_area_init_core()".

- Baoquan has also redone some MM initializatio code in the series
"mm/init: minor clean up and improvement".

- MM helper cleanups from Christoph Hellwig in his series "remove
follow_pfn".

- More cleanups from Matthew Wilcox in the series "Various
page->flags cleanups".

- Vlastimil Babka has contributed maintainability improvements in the
series "memcg_kmem hooks refactoring".

- More folio conversions and cleanups in Matthew Wilcox's series:
"Convert huge_zero_page to huge_zero_folio"
"khugepaged folio conversions"
"Remove page_idle and page_young wrappers"
"Use folio APIs in procfs"
"Clean up __folio_put()"
"Some cleanups for memory-failure"
"Remove page_mapping()"
"More folio compat code removal"

- David Hildenbrand chipped in with "fs/proc/task_mmu: convert
hugetlb functions to work on folis".

- Code consolidation and cleanup work related to GUP's handling of
hugetlbs in Peter Xu's series "mm/gup: Unify hugetlb, part 2".

- Rick Edgecombe has developed some fixes to stack guard gaps in the
series "Cover a guard gap corner case".

- Jinjiang Tu has fixed KSM's behaviour after a fork+exec in the
series "mm/ksm: fix ksm exec support for prctl".

- Baolin Wang has implemented NUMA balancing for multi-size THPs.
This is a simple first-cut implementation for now. The series is
"support multi-size THP numa balancing".

- Cleanups to vma handling helper functions from Matthew Wilcox in
the series "Unify vma_address and vma_pgoff_address".

- Some selftests maintenance work from Dev Jain in the series
"selftests/mm: mremap_test: Optimizations and style fixes".

- Improvements to the swapping of multi-size THPs from Ryan Roberts
in the series "Swap-out mTHP without splitting".

- Kefeng Wang has significantly optimized the handling of arm64's
permission page faults in the series
"arch/mm/fault: accelerate pagefault when badaccess"
"mm: remove arch's private VM_FAULT_BADMAP/BADACCESS"

- GUP cleanups from David Hildenbrand in "mm/gup: consistently call
it GUP-fast".

- hugetlb fault code cleanups from Vishal Moola in "Hugetlb fault
path to use struct vm_fault".

- selftests build fixes from John Hubbard in the series "Fix
selftests/mm build without requiring "make headers"".

- Memory tiering fixes/improvements from Ho-Ren (Jack) Chuang in the
series "Improved Memory Tier Creation for CPUless NUMA Nodes".
Fixes the initialization code so that migration between different
memory types works as intended.

- David Hildenbrand has improved follow_pte() and fixed an errant
driver in the series "mm: follow_pte() improvements and acrn
follow_pte() fixes".

- David also did some cleanup work on large folio mapcounts in his
series "mm: mapcount for large folios + page_mapcount() cleanups".

- Folio conversions in KSM in Alex Shi's series "transfer page to
folio in KSM".

- Barry Song has added some sysfs stats for monitoring multi-size
THP's in the series "mm: add per-order mTHP alloc and swpout
counters".

- Some zswap cleanups from Yosry Ahmed in the series "zswap
same-filled and limit checking cleanups".

- Matthew Wilcox has been looking at buffer_head code and found the
documentation to be lacking. The series is "Improve buffer head
documentation".

- Multi-size THPs get more work, this time from Lance Yang. His
series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free"
optimizes the freeing of these things.

- Kemeng Shi has added more userspace-visible writeback
instrumentation in the series "Improve visibility of writeback".

- Kemeng Shi then sent some maintenance work on top in the series
"Fix and cleanups to page-writeback".

- Matthew Wilcox reduces mmap_lock traffic in the anon vma code in
the series "Improve anon_vma scalability for anon VMAs". Intel's
test bot reported an improbable 3x improvement in one test.

- SeongJae Park adds some DAMON feature work in the series
"mm/damon: add a DAMOS filter type for page granularity access recheck"
"selftests/damon: add DAMOS quota goal test"

- Also some maintenance work in the series
"mm/damon/paddr: simplify page level access re-check for pageout"
"mm/damon: misc fixes and improvements"

- David Hildenbrand has disabled some known-to-fail selftests ni the
series "selftests: mm: cow: flag vmsplice() hugetlb tests as
XFAIL".

- memcg metadata storage optimizations from Shakeel Butt in "memcg:
reduce memory consumption by memcg stats".

- DAX fixes and maintenance work from Vishal Verma in the series
"dax/bus.c: Fixups for dax-bus locking""

* tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (426 commits)
memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_order
selftests/mm: hugetlb_madv_vs_map: avoid test skipping by querying hugepage size at runtime
mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_wp
mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_fault
selftests: cgroup: add tests to verify the zswap writeback path
mm: memcg: make alloc_mem_cgroup_per_node_info() return bool
mm/damon/core: fix return value from damos_wmark_metric_value
mm: do not update memcg stats for NR_{FILE/SHMEM}_PMDMAPPED
selftests: cgroup: remove redundant enabling of memory controller
Docs/mm/damon/maintainer-profile: allow posting patches based on damon/next tree
Docs/mm/damon/maintainer-profile: change the maintainer's timezone from PST to PT
Docs/mm/damon/design: use a list for supported filters
Docs/admin-guide/mm/damon/usage: fix wrong schemes effective quota update command
Docs/admin-guide/mm/damon/usage: fix wrong example of DAMOS filter matching sysfs file
selftests/damon: classify tests for functionalities and regressions
selftests/damon/_damon_sysfs: use 'is' instead of '==' for 'None'
selftests/damon/_damon_sysfs: find sysfs mount point from /proc/mounts
selftests/damon/_damon_sysfs: check errors from nr_schemes file reads
mm/damon/core: initialize ->esz_bp from damos_quota_init_priv()
selftests/damon: add a test for DAMOS quota goal
...

mm/execmem, arch: convert simple overrides of module_alloc to execmem

2024-05-14T07:31:43+00:00

Several architectures override module_alloc() only to define address
range for code allocations different than VMALLOC address space.

Provide a generic implementation in execmem that uses the parameters for
address space ranges, required alignment and page protections provided
by architectures.

The architectures must fill execmem_info structure and implement
execmem_arch_setup() that returns a pointer to that structure. This way the
execmem initialization won't be called from every architecture, but rather
from a central place, namely a core_initcall() in execmem.

The execmem provides execmem_alloc() API that wraps __vmalloc_node_range()
with the parameters defined by the architectures.  If an architecture does
not implement execmem_arch_setup(), execmem_alloc() will fall back to
module_alloc().

Signed-off-by: Mike Rapoport (IBM) 
Acked-by: Song Liu 
Reviewed-by: Masami Hiramatsu (Google) 
Signed-off-by: Luis Chamberlain

mm: init_mlocked_on_free_v3

2024-04-26T03:56:29+00:00

Implements the "init_mlocked_on_free" boot option. When this boot option
is enabled, any mlock'ed pages are zeroed on free. If
the pages are munlock'ed beforehand, no initialization takes place.
This boot option is meant to combat the performance hit of
"init_on_free" as reported in commit 6471384af2a6 ("mm: security:
introduce init_on_alloc=1 and init_on_free=1 boot options"). With
"init_mlocked_on_free=1" only relevant data is freed while everything
else is left untouched by the kernel. Correspondingly, this patch
introduces no performance hit for unmapping non-mlock'ed memory. The
unmapping overhead for purely mlocked memory was measured to be
approximately 13%. Realistically, most systems mlock only a fraction of
the total memory so the real-world system overhead should be close to
zero.

Optimally, userspace programs clear any key material or other
confidential memory before exit and munlock the according memory
regions. If a program crashes, userspace key managers fail to do this
job. Accordingly, no munlock operations are performed so the data is
caught and zeroed by the kernel. Should the program not crash, all
memory will ideally be munlocked so no overhead is caused.

CONFIG_INIT_MLOCKED_ON_FREE_DEFAULT_ON can be set to enable
"init_mlocked_on_free" by default.

Link: https://lkml.kernel.org/r/20240329145605.149917-1-yjnworkstation@gmail.com
Signed-off-by: York Jasper Niebuhr 
Cc: Matthew Wilcox (Oracle) 
Cc: York Jasper Niebuhr 
Cc: Kees Cook 
Signed-off-by: Andrew Morton

mm/mm_init.c: remove the outdated code comment above deferred_grow_zone()

2024-04-26T03:56:17+00:00

The noinline attribute has been taken off in commit 9420f89db2dd ("mm:
move most of core MM initialization to mm/mm_init.c").  So remove the
unneeded code comment above deferred_grow_zone().

And also remove the unneeded bracket in deferred_init_pages().

Link: https://lkml.kernel.org/r/20240326061134.1055295-6-bhe@redhat.com
Signed-off-by: Baoquan He 
Reviewed-by: Mike Rapoport (IBM) 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton

mm: make __absent_pages_in_range() as static

2024-04-26T03:56:17+00:00

It's only called in mm/mm_init.c now.

Link: https://lkml.kernel.org/r/20240326061134.1055295-4-bhe@redhat.com
Signed-off-by: Baoquan He 
Reviewed-by: Mike Rapoport (IBM) 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton

mm/init: remove the unnecessary special treatment for memory-less node

2024-04-26T03:56:16+00:00

Because memory-less node's ->node_present_pages and its zone's
->present_pages are all 0, the judgement before calling node_set_state()
to set N_MEMORY, N_HIGH_MEMORY, N_NORMAL_MEMORY for node is enough to skip
memory-less node.  The 'continue;' statement inside for_each_node() loop
of free_area_init() is gilding the lily.

Here, remove the special handling to make memory-less node share the same
code flow as normal node.

And also rephrase the code comments above the 'continue' statement
and move them above above line 'if (pgdat->node_present_pages)'.

[bhe@redhat.com: redo code comments, per Mike]
  Link: https://lkml.kernel.org/r/ZhYJAVQRYJSTKZng@MiWiFi-R3L-srv
Link: https://lkml.kernel.org/r/20240326061134.1055295-3-bhe@redhat.com
Signed-off-by: Baoquan He 
Cc: Mel Gorman 
Cc: "Mike Rapoport (IBM)" 
Signed-off-by: Andrew Morton

mm/mm_init.c: remove arch_reserved_kernel_pages()

2024-04-26T03:56:11+00:00

Since the current calculation of calc_nr_kernel_pages() has taken into
consideration of kernel reserved memory, no need to have
arch_reserved_kernel_pages() any more.

Link: https://lkml.kernel.org/r/20240325145646.1044760-7-bhe@redhat.com
Signed-off-by: Baoquan He 
Reviewed-by: Mike Rapoport (IBM) 
Signed-off-by: Andrew Morton

mm/mm_init.c: remove unneeded calc_memmap_size()

2024-04-26T03:56:11+00:00

Nobody calls calc_memmap_size() now.

Link: https://lkml.kernel.org/r/20240325145646.1044760-6-bhe@redhat.com
Signed-off-by: Baoquan He 
Reviewed-by: Mike Rapoport (IBM) 
Signed-off-by: Andrew Morton

mm/mm_init.c: remove meaningless calculation of zone->managed_pages in free_area_init_core()

2024-04-26T03:56:10+00:00

Currently, in free_area_init_core(), when initialize zone's field, a rough
value is set to zone->managed_pages.  That value is calculated by
(zone->present_pages - memmap_pages).

In the meantime, add the value to nr_all_pages and nr_kernel_pages which
represent all free pages of system (only low memory or including HIGHMEM
memory separately).  Both of them are gonna be used in
alloc_large_system_hash().

However, the rough calculation and setting of zone->managed_pages is
meaningless because
  a) memmap pages are allocated on units of node in sparse_init() or
     alloc_node_mem_map(pgdat); The simple (zone->present_pages -
     memmap_pages) is too rough to make sense for zone;
  b) the set zone->managed_pages will be zeroed out and reset with
     acutal value in mem_init() via memblock_free_all(). Before the
     resetting, no buddy allocation request is issued.

Here, remove the meaningless and complicated calculation of
(zone->present_pages - memmap_pages), directly set zone->managed_pages as
zone->present_pages for now.  It will be adjusted in mem_init().

And also remove the assignment of nr_all_pages and nr_kernel_pages in
free_area_init_core().  Instead, call the newly added
calc_nr_kernel_pages() to count up all free but not reserved memory in
memblock and assign to nr_all_pages and nr_kernel_pages.  The counting
excludes memmap_pages, and other kernel used data, which is more accurate
than old way and simpler, and can also cover the ppc required
arch_reserved_kernel_pages() case.

And also clean up the outdated code comment above free_area_init_core(). 
And free_area_init_core() is easy to understand now, no need to add words
to explain.

[bhe@redhat.com: initialize zone->managed_pages as zone->present_pages for now]
  Link: https://lkml.kernel.org/r/ZgU0bsJ2FEjykvju@MiWiFi-R3L-srv
Link: https://lkml.kernel.org/r/20240325145646.1044760-5-bhe@redhat.com
Signed-off-by: Baoquan He 
Reviewed-by: Mike Rapoport (IBM) 
Signed-off-by: Andrew Morton