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Aristeu Rozanski c311d65129 hugetlb: force allocating surplus hugepages on mempolicy allowed nodes 
commit 003af997c8 upstream.

When trying to allocate a hugepage with no reserved ones free, it may be
allowed in case a number of overcommit hugepages was configured (using
/proc/sys/vm/nr_overcommit_hugepages) and that number wasn't reached.
This allows for a behavior of having extra hugepages allocated
dynamically, if there're resources for it.  Some sysadmins even prefer not
reserving any hugepages and setting a big number of overcommit hugepages.

But while attempting to allocate overcommit hugepages in a multi node
system (either NUMA or mempolicy/cpuset) said allocations might randomly
fail even when there're resources available for the allocation.

This happens due to allowed_mems_nr() only accounting for the number of
free hugepages in the nodes the current process belongs to and the surplus
hugepage allocation is done so it can be allocated in any node.  In case
one or more of the requested surplus hugepages are allocated in a
different node, the whole allocation will fail due allowed_mems_nr()
returning a lower value.

So allocate surplus hugepages in one of the nodes the current process
belongs to.

Easy way to reproduce this issue is to use a 2+ NUMA nodes system:

	# echo 0 >/proc/sys/vm/nr_hugepages
	# echo 1 >/proc/sys/vm/nr_overcommit_hugepages
	# numactl -m0 ./tools/testing/selftests/mm/map_hugetlb 2

Repeating the execution of map_hugetlb test application will eventually
fail when the hugepage ends up allocated in a different node.

[aris@ruivo.org: v2]
  Link: https://lkml.kernel.org/r/20240701212343.GG844599@cathedrallabs.org
Link: https://lkml.kernel.org/r/20240621190050.mhxwb65zn37doegp@redhat.com
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Aristeu Rozanski <aris@ruivo.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Vishal Moola <vishal.moola@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-08-03 08:54:11 +02:00
arch LoongArch: Check TIF_LOAD_WATCH to enable user space watchpoint 2024-08-03 08:54:11 +02:00
block block/mq-deadline: Fix the tag reservation code 2024-08-03 08:53:22 +02:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: aead,cipher - zeroize key buffer after use 2024-07-11 12:49:04 +02:00
Documentation scsi: sr: Fix unintentional arithmetic wraparound 2024-07-25 09:50:40 +02:00
drivers s390/dasd: fix error checks in dasd_copy_pair_store() 2024-08-03 08:54:10 +02:00
fs fs/ntfs3: Keep runs for $MFT::$ATTR_DATA and $MFT::$ATTR_BITMAP 2024-08-03 08:54:10 +02:00
include sbitmap: fix io hung due to race on sbitmap_word::cleared 2024-08-03 08:54:11 +02:00
init smp: Provide 'setup_max_cpus' definition on UP too 2024-06-16 13:47:49 +02:00
io_uring io_uring/rsrc: fix incorrect assignment of iter->nr_segs in io_import_fixed 2024-06-27 13:49:10 +02:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel bpf: Eliminate remaining "make W=1" warnings in kernel/bpf/btf.o 2024-08-03 08:53:43 +02:00
lib sbitmap: fix io hung due to race on sbitmap_word::cleared 2024-08-03 08:54:11 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm hugetlb: force allocating surplus hugepages on mempolicy allowed nodes 2024-08-03 08:54:11 +02:00
net ipv4: Fix incorrect TOS in fibmatch route get reply 2024-08-03 08:54:05 +02:00
rust rust: kernel: require Send for Module implementations 2024-05-17 12:01:56 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:24:47 +01:00
scripts x86/kconfig: Add as-instr64 macro to properly evaluate AS_WRUSS 2024-08-03 08:53:21 +02:00
security landlock: Don't lose track of restrictions on cred_transfer 2024-08-03 08:54:11 +02:00
sound ASoC: amd: Adjust error handling in case of absent codec device 2024-08-03 08:54:00 +02:00
tools ipv4: Fix incorrect TOS in fibmatch route get reply 2024-08-03 08:54:05 +02:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:49:11 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS pwm: Rename pwm_apply_state() to pwm_apply_might_sleep() 2024-06-12 11:12:24 +02:00
Makefile Linux 6.6.43 2024-07-27 11:34:11 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.