97769a53f1
Tracing BPF programs execute from tracepoints and kprobes where running context is unknown, but they need to request additional memory. The prior workarounds were using pre-allocated memory and BPF specific freelists to satisfy such allocation requests. Instead, introduce gfpflags_allow_spinning() condition that signals to the allocator that running context is unknown. Then rely on percpu free list of pages to allocate a page. try_alloc_pages() -> get_page_from_freelist() -> rmqueue() -> rmqueue_pcplist() will spin_trylock to grab the page from percpu free list. If it fails (due to re-entrancy or list being empty) then rmqueue_bulk()/rmqueue_buddy() will attempt to spin_trylock zone->lock and grab the page from there. spin_trylock() is not safe in PREEMPT_RT when in NMI or in hard IRQ. Bailout early in such case. The support for gfpflags_allow_spinning() mode for free_page and memcg comes in the next patches. This is a first step towards supporting BPF requirements in SLUB and getting rid of bpf_mem_alloc. That goal was discussed at LSFMM: https://lwn.net/Articles/974138/ Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/r/20250222024427.30294-3-alexei.starovoitov@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.