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Roman Gushchin 9f1edf1aed mm: readahead: make thp readahead conditional to mmap_miss logic 
Commit 4687fdbb80 ("mm/filemap: Support VM_HUGEPAGE for file mappings")
introduced a special handling for VM_HUGEPAGE mappings: even if the
readahead is disabled, 1 or 2 HPAGE_PMD_ORDER pages are allocated.

This change causes a significant regression for containers with a tight
memory.max limit, if VM_HUGEPAGE is widely used.  Prior to this commit,
mmap_miss logic would eventually lead to the readahead disablement,
effectively reducing the memory pressure in the cgroup.  With this change
the kernel is trying to allocate 1-2 huge pages for each fault, no matter
if these pages are used or not before being evicted, increasing the memory
pressure multi-fold.

To fix the regression, let's make the new VM_HUGEPAGE conditional to the
mmap_miss check, but keep independent from the ra->ra_pages.  This way the
main intention of commit 4687fdbb80 ("mm/filemap: Support VM_HUGEPAGE
for file mappings") stays intact, but the regression is resolved.

The logic behind this changes is simple: even if a user explicitly
requests using huge pages to back the file mapping (using VM_HUGEPAGE
flag), under a very strong memory pressure it's better to fall back to
ordinary pages.

Link: https://lkml.kernel.org/r/20251006175106.377411-1-roman.gushchin@linux.dev
Fixes: 4687fdbb80 ("mm/filemap: Support VM_HUGEPAGE for file mappings")
Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-16 17:27:56 -08:00
arch mm: fix MAX_FOLIO_ORDER on powerpc configs with hugetlb 2025-11-15 10:52:00 -08:00
block block-6.18-20251031 2025-10-31 12:57:19 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push contains the following changes: 2025-10-10 08:56:16 -07:00
Documentation gpio fixes for v6.18-rc5 2025-11-07 08:10:55 -08:00
drivers i2c-for-6.18-rc5 2025-11-09 09:29:44 -08:00
fs nilfs2: avoid having an active sc_timer before freeing sci 2025-11-09 21:19:46 -08:00
include mm/ksm: fix exec/fork inheritance support for prctl 2025-11-16 17:27:55 -08:00
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring: fix regbuf vector size truncation 2025-11-07 17:17:13 -07:00
ipc namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
kernel crash: fix crashkernel resource shrink 2025-11-15 10:52:01 -08:00
lib lib/test_vmalloc: remove xfail condition check 2025-11-16 17:27:53 -08:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm mm: readahead: make thp readahead conditional to mmap_miss logic 2025-11-16 17:27:56 -08:00
net Including fixes from bluetooth and wireless. 2025-11-06 08:52:30 -08:00
rust rust: kbuild: workaround rustdoc doctests modifier bug 2025-11-04 00:00:06 +01:00
samples Char/Misc/IIO/Binder changes for 6.18-rc1 2025-10-04 16:26:32 -07:00
scripts scripts/decode_stacktrace.sh: fix build ID and PC source parsing 2025-11-09 21:19:45 -08:00
security integrity-v6.18 2025-10-05 10:48:33 -07:00
sound ASoC: Fixes for v6.18 2025-10-30 13:08:08 +01:00
tools selftests: update ksm inheritance tests for prctl fork/exec 2025-11-16 17:27:55 -08:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt KVM x86 fixes for 6.18: 2025-10-18 10:25:43 +02:00
.clang-format memblock: drop for_each_free_mem_pfn_range_in_zone_from() 2025-09-14 08:49:03 +03:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore compile_commands.json globally 2025-08-12 15:53:55 -07:00
.mailmap MAINTAINERS: update David Hildenbrand's email address 2025-11-15 10:52:01 -08:00
.pylintrc tools: docs: parse-headers.py: move it from sphinx dir 2025-08-29 15:54:42 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: mark ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS MAINTAINERS: update David Hildenbrand's email address 2025-11-15 10:52:01 -08:00
Makefile Linux 6.18-rc5 2025-11-09 15:10:19 -08:00
README README: Fix spelling 2024-03-18 03:36:32 -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 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.