linux-stable.git/include/linux/hugetlb.h, branch v6.11.2

mm/hugetlb: fix hugetlb vs. core-mm PT locking

2024-08-16T05:16:13+00:00

We recently made GUP's common page table walking code to also walk hugetlb
VMAs without most hugetlb special-casing, preparing for the future of
having less hugetlb-specific page table walking code in the codebase. 
Turns out that we missed one page table locking detail: page table locking
for hugetlb folios that are not mapped using a single PMD/PUD.

Assume we have hugetlb folio that spans multiple PTEs (e.g., 64 KiB
hugetlb folios on arm64 with 4 KiB base page size).  GUP, as it walks the
page tables, will perform a pte_offset_map_lock() to grab the PTE table
lock.

However, hugetlb that concurrently modifies these page tables would
actually grab the mm->page_table_lock: with USE_SPLIT_PTE_PTLOCKS, the
locks would differ.  Something similar can happen right now with hugetlb
folios that span multiple PMDs when USE_SPLIT_PMD_PTLOCKS.

This issue can be reproduced [1], for example triggering:

[ 3105.936100] ------------[ cut here ]------------
[ 3105.939323] WARNING: CPU: 31 PID: 2732 at mm/gup.c:142 try_grab_folio+0x11c/0x188
[ 3105.944634] Modules linked in: [...]
[ 3105.974841] CPU: 31 PID: 2732 Comm: reproducer Not tainted 6.10.0-64.eln141.aarch64 #1
[ 3105.980406] Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20240524-4.fc40 05/24/2024
[ 3105.986185] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 3105.991108] pc : try_grab_folio+0x11c/0x188
[ 3105.994013] lr : follow_page_pte+0xd8/0x430
[ 3105.996986] sp : ffff80008eafb8f0
[ 3105.999346] x29: ffff80008eafb900 x28: ffffffe8d481f380 x27: 00f80001207cff43
[ 3106.004414] x26: 0000000000000001 x25: 0000000000000000 x24: ffff80008eafba48
[ 3106.009520] x23: 0000ffff9372f000 x22: ffff7a54459e2000 x21: ffff7a546c1aa978
[ 3106.014529] x20: ffffffe8d481f3c0 x19: 0000000000610041 x18: 0000000000000001
[ 3106.019506] x17: 0000000000000001 x16: ffffffffffffffff x15: 0000000000000000
[ 3106.024494] x14: ffffb85477fdfe08 x13: 0000ffff9372ffff x12: 0000000000000000
[ 3106.029469] x11: 1fffef4a88a96be1 x10: ffff7a54454b5f0c x9 : ffffb854771b12f0
[ 3106.034324] x8 : 0008000000000000 x7 : ffff7a546c1aa980 x6 : 0008000000000080
[ 3106.038902] x5 : 00000000001207cf x4 : 0000ffff9372f000 x3 : ffffffe8d481f000
[ 3106.043420] x2 : 0000000000610041 x1 : 0000000000000001 x0 : 0000000000000000
[ 3106.047957] Call trace:
[ 3106.049522]  try_grab_folio+0x11c/0x188
[ 3106.051996]  follow_pmd_mask.constprop.0.isra.0+0x150/0x2e0
[ 3106.055527]  follow_page_mask+0x1a0/0x2b8
[ 3106.058118]  __get_user_pages+0xf0/0x348
[ 3106.060647]  faultin_page_range+0xb0/0x360
[ 3106.063651]  do_madvise+0x340/0x598

Let's make huge_pte_lockptr() effectively use the same PT locks as any
core-mm page table walker would.  Add ptep_lockptr() to obtain the PTE
page table lock using a pte pointer -- unfortunately we cannot convert
pte_lockptr() because virt_to_page() doesn't work with kmap'ed page tables
we can have with CONFIG_HIGHPTE.

Handle CONFIG_PGTABLE_LEVELS correctly by checking in reverse order, such
that when e.g., CONFIG_PGTABLE_LEVELS==2 with
PGDIR_SIZE==P4D_SIZE==PUD_SIZE==PMD_SIZE will work as expected.  Document
why that works.

There is one ugly case: powerpc 8xx, whereby we have an 8 MiB hugetlb
folio being mapped using two PTE page tables.  While hugetlb wants to take
the PMD table lock, core-mm would grab the PTE table lock of one of both
PTE page tables.  In such corner cases, we have to make sure that both
locks match, which is (fortunately!) currently guaranteed for 8xx as it
does not support SMP and consequently doesn't use split PT locks.

[1] https://lore.kernel.org/all/1bbfcc7f-f222-45a5-ac44-c5a1381c596d@redhat.com/

Link: https://lkml.kernel.org/r/20240801204748.99107-1-david@redhat.com
Fixes: 9cb28da54643 ("mm/gup: handle hugetlb in the generic follow_page_mask code")
Signed-off-by: David Hildenbrand 
Acked-by: Peter Xu 
Reviewed-by: Baolin Wang 
Tested-by: Baolin Wang 
Cc: Peter Xu 
Cc: Oscar Salvador 
Cc: Muchun Song 
Cc: 
Signed-off-by: Andrew Morton

mm/hugetlb: fix possible recursive locking detected warning

2024-07-18T04:08:54+00:00

When tries to demote 1G hugetlb folios, a lockdep warning is observed:

============================================
WARNING: possible recursive locking detected
6.10.0-rc6-00452-ga4d0275fa660-dirty #79 Not tainted
--------------------------------------------
bash/710 is trying to acquire lock:
ffffffff8f0a7850 (&h->resize_lock){+.+.}-{3:3}, at: demote_store+0x244/0x460

but task is already holding lock:
ffffffff8f0a6f48 (&h->resize_lock){+.+.}-{3:3}, at: demote_store+0xae/0x460

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&h->resize_lock);
  lock(&h->resize_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

4 locks held by bash/710:
 #0: ffff8f118439c3f0 (sb_writers#5){.+.+}-{0:0}, at: ksys_write+0x64/0xe0
 #1: ffff8f11893b9e88 (&of->mutex#2){+.+.}-{3:3}, at: kernfs_fop_write_iter+0xf8/0x1d0
 #2: ffff8f1183dc4428 (kn->active#98){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x100/0x1d0
 #3: ffffffff8f0a6f48 (&h->resize_lock){+.+.}-{3:3}, at: demote_store+0xae/0x460

stack backtrace:
CPU: 3 PID: 710 Comm: bash Not tainted 6.10.0-rc6-00452-ga4d0275fa660-dirty #79
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
 
 dump_stack_lvl+0x68/0xa0
 __lock_acquire+0x10f2/0x1ca0
 lock_acquire+0xbe/0x2d0
 __mutex_lock+0x6d/0x400
 demote_store+0x244/0x460
 kernfs_fop_write_iter+0x12c/0x1d0
 vfs_write+0x380/0x540
 ksys_write+0x64/0xe0
 do_syscall_64+0xb9/0x1d0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa61db14887
RSP: 002b:00007ffc56c48358 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fa61db14887
RDX: 0000000000000002 RSI: 000055a030050220 RDI: 0000000000000001
RBP: 000055a030050220 R08: 00007fa61dbd1460 R09: 000000007fffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007fa61dc1b780 R14: 00007fa61dc17600 R15: 00007fa61dc16a00
 

Lockdep considers this an AA deadlock because the different resize_lock
mutexes reside in the same lockdep class, but this is a false positive.
Place them in distinct classes to avoid these warnings.

Link: https://lkml.kernel.org/r/20240712031314.2570452-1-linmiaohe@huawei.com
Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support")
Signed-off-by: Miaohe Lin 
Acked-by: Muchun Song 
Cc: 
Signed-off-by: Andrew Morton

mm: remove CONFIG_ARCH_HAS_HUGEPD

2024-07-12T22:52:19+00:00

powerpc was the only user of CONFIG_ARCH_HAS_HUGEPD and doesn't use it
anymore, so remove all related code.

Link: https://lkml.kernel.org/r/4b10c54c794780b955f3ad6c657d0199dd792146.1719928057.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy 
Acked-by: Oscar Salvador 
Cc: Jason Gunthorpe 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Peter Xu 
Signed-off-by: Andrew Morton

mm/hugetlb_cgroup: switch to the new cftypes

2024-07-04T02:30:10+00:00

The previous patch has already reconstructed the cftype attributes based
on the templates and saved them in dfl_cftypes and legacy_cftypes.  then
remove the old procedure and switch to the new cftypes.

Link: https://lkml.kernel.org/r/20240612092409.2027592-4-xiujianfeng@huawei.com
Signed-off-by: Xiu Jianfeng 
Cc: Muchun Song 
Cc: Oscar Salvador 
Signed-off-by: Andrew Morton

mm/hugetlb: mm/memory_hotplug: use a folio in scan_movable_pages()

2024-07-04T02:30:02+00:00

By using a folio in scan_movable_pages() we convert the last user of the
page-based hugetlb information macro functions to the folio version. 
After this conversion, we can safely remove the page-based definitions
from include/linux/hugetlb.h.

Link: https://lkml.kernel.org/r/20240530171427.242018-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar 
Acked-by: David Hildenbrand 
Cc: Matthew Wilcox (Oracle) 
Cc: Muchun Song 
Cc: Oscar Salvador 
Signed-off-by: Andrew Morton

mm/hugetlb: remove {Set,Clear}Hpage macros

2024-07-04T02:29:56+00:00

All users have been converted to use the folio version of these macros, we
can safely remove the page based interface.

Link: https://lkml.kernel.org/r/20240520224407.110062-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar 
Reviewed-by: Matthew Wilcox (Oracle) 
Reviewed-by: David Hildenbrand 
Reviewed-by: Oscar Salvador 
Cc: Muchun Song 
Cc: Peter Xu 
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: convert hugetlb_page_mapping_lock_write to folio

2024-05-06T00:53:46+00:00

The page is only used to get the mapping, so the folio will do just as
well.  Both callers already have a folio available, so this saves a call
to compound_head().

Link: https://lkml.kernel.org/r/20240412193510.2356957-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Jane Chu  
Reviewed-by: Oscar Salvador 
Acked-by: Miaohe Lin 
Cc: Dan Williams 
Signed-off-by: Andrew Morton

mm/hugetlb: rename dissolve_free_huge_pages() to dissolve_free_hugetlb_folios()

2024-05-06T00:53:35+00:00

dissolve_free_huge_pages() only uses folios internally, rename it to
dissolve_free_hugetlb_folios() and change the comments which reference it.

[akpm@linux-foundation.org: remove unneeded `extern']
Link: https://lkml.kernel.org/r/20240412182139.120871-2-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar 
Reviewed-by: Vishal Moola (Oracle) 
Reviewed-by: Miaohe Lin 
Cc: Jane Chu 
Cc: Matthew Wilcox (Oracle) 
Cc: Muchun Song 
Cc: Oscar Salvador 
Signed-off-by: Andrew Morton

mm/hugetlb: convert dissolve_free_huge_pages() to folios

2024-05-06T00:53:35+00:00

Allows us to rename dissolve_free_huge_pages() to
dissolve_free_hugetlb_folio(). Convert one caller to pass in a folio
directly and use page_folio() to convert the caller in mm/memory-failure.

[sidhartha.kumar@oracle.com: remove unneeded `extern']
  Link: https://lkml.kernel.org/r/71760ed4-e80d-493a-95ea-2545414b1aba@oracle.com
[sidhartha.kumar@oracle.com: v2]
  Link: https://lkml.kernel.org/r/20240412182139.120871-1-sidhartha.kumar@oracle.com
Link: https://lkml.kernel.org/r/20240411164756.261178-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar 
Reviewed-by: Oscar Salvador 
Reviewed-by: Vishal Moola (Oracle) 
Reviewed-by: Miaohe Lin 
Cc: Jane Chu 
Cc: Matthew Wilcox (Oracle) 
Cc: Muchun Song 
Signed-off-by: Andrew Morton