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Add a test to ensure function call specialization is
done per-call site. Use bpf_dynptr_from_file that has
observably different behavior between its sleepable and
nonsleepable versions. The sleepable path fails in the
sleepable __kernel_read() call with -EIO, while the
nonsleepable fails in the page-cache lookup path with
-EFAULT. Test that whatever the order the nonsleepable
and sleepable calls are made in the program, both
call sites use the correct specialized kfunc.
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261002105218.6171-8-emil@etsalapatis.com
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The file_reader/on_open_expect_fault fails consistently on my system.
It expects a page fault on first dynptr read of some range the exe
file of the current process because it has paged out that page range
earlier. However a lot can happen to that range (which depending on
the actual memory layout could contain text section, data section,
sections )related to dynamic linking...) between the moment it was
paged out and the moment the bpf program expected to hit a pagefault
actually run.
A bit of instrumentation with mincore() shows that pages from that
range were accessed several times before the program is run. In
particular the call of file_reader__load() seems to fault all the
range in.
Move the call to madvise(MADV_PAGEOUT) to just before attaching the
program to minimize the risk of having those page pulled back in from
under our feet.
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20260420134637.2513867-1-jmarchan@redhat.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
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file_reader/on_open_expect_fault intermittently fails when test_progs
runs tests in parallel, because it expects a page fault on first read.
Another file_reader test running concurrently may have already pulled
the same pages into the page cache, eliminating the fault and causing a
spurious failure.
Make file_reader/on_open_expect_fault read from a file region that does
not overlap with other file_reader tests, so the initial access still
faults even under parallel execution.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20251029195907.858217-1-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Introducing selftests for validating file-backed dynptr works as
expected.
* validate implementation supports dynptr slice and read operations
* validate destructors should be paired with initializers
* validate sleepable progs can page in.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251026203853.135105-11-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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