mirror of
https://github.com/torvalds/linux.git
synced 2024-11-22 12:11:40 +00:00
A mirror of the official Linux kernel repository just in case
003af997c8
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> |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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 reStructuredText 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.