Improve BPF test stability (related to perf events and scheduling) #92
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Master branch: b664e25 |
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In send_signal, replace sleep with dummy cpu intensive computation to increase probability of child process being scheduled. Add few more asserts. In find_vma, reduce sample_freq as higher values may be rejected in some qemu setups, remove usleep and increase length of cpu intensive computation. In bpf_cookie, perf_link and perf_branches, reduce sample_freq as higher values may be rejected in some qemu setups Signed-off-by: Mykola Lysenko <mykolal@fb.com>
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=618976 expired. Closing PR. |
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The per-channel data is available directly in the driver data struct. So
use it without making use of pwm_[gs]et_chip_data().
The relevant change introduced by this patch to lpc18xx_pwm_disable() at
the assembler level (for an arm lpc18xx_defconfig build) is:
push {r3, r4, r5, lr}
mov r4, r0
mov r0, r1
mov r5, r1
bl 0 <pwm_get_chip_data>
ldr r3, [r0, #0]
changes to
ldr r3, [r1, #8]
push {r4, lr}
add.w r3, r0, r3, lsl #2
ldr r3, [r3, #92] ; 0x5c
So this reduces stack usage, has an improved runtime behavior because of
better pipeline usage, doesn't branch to an external function and the
generated code is a bit smaller occupying less memory.
The codesize of lpc18xx_pwm_probe() is reduced by 32 bytes.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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BPF CI fails for arm64 and s390x each with the following result: [...] All error logs: serial_test_kprobe_multi_bench_attach:PASS:get_syms 0 nsec serial_test_kprobe_multi_bench_attach:PASS:kprobe_multi_empty__open_and_load 0 nsec libbpf: prog 'test_kprobe_empty': failed to attach: Operation not supported serial_test_kprobe_multi_bench_attach:FAIL:bpf_program__attach_kprobe_multi_opts unexpected error: -95 #92 kprobe_multi_bench_attach:FAIL [...] Add the test to the deny list. Fixes: 5b6c7e5 ("selftests/bpf: Add attach bench test") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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BPF CI fails for arm64 and s390x each with the following result: [...] All error logs: serial_test_kprobe_multi_bench_attach:PASS:get_syms 0 nsec serial_test_kprobe_multi_bench_attach:PASS:kprobe_multi_empty__open_and_load 0 nsec libbpf: prog 'test_kprobe_empty': failed to attach: Operation not supported serial_test_kprobe_multi_bench_attach:FAIL:bpf_program__attach_kprobe_multi_opts unexpected error: -95 #92 kprobe_multi_bench_attach:FAIL [...] Add the test to the deny list. Fixes: 5b6c7e5 ("selftests/bpf: Add attach bench test") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
kernel-patches-daemon-bpf-rc bot
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If track_pfn_copy() fails, we already added the dst VMA to the maple tree. As fork() fails, we'll cleanup the maple tree, and stumble over the dst VMA for which we neither performed any reservation nor copied any page tables. Consequently untrack_pfn() will see VM_PAT and try obtaining the PAT information from the page table -- which fails because the page table was not copied. The easiest fix would be to simply clear the VM_PAT flag of the dst VMA if track_pfn_copy() fails. However, the whole thing is about "simply" clearing the VM_PAT flag is shaky as well: if we passed track_pfn_copy() and performed a reservation, but copying the page tables fails, we'll simply clear the VM_PAT flag, not properly undoing the reservation ... which is also wrong. So let's fix it properly: set the VM_PAT flag only if the reservation succeeded (leaving it clear initially), and undo the reservation if anything goes wrong while copying the page tables: clearing the VM_PAT flag after undoing the reservation. Note that any copied page table entries will get zapped when the VMA will get removed later, after copy_page_range() succeeded; as VM_PAT is not set then, we won't try cleaning VM_PAT up once more and untrack_pfn() will be happy. Note that leaving these page tables in place without a reservation is not a problem, as we are aborting fork(); this process will never run. A reproducer can trigger this usually at the first try: https://gitlab.com/davidhildenbrand/scratchspace/-/raw/main/reproducers/pat_fork.c WARNING: CPU: 26 PID: 11650 at arch/x86/mm/pat/memtype.c:983 get_pat_info+0xf6/0x110 Modules linked in: ... CPU: 26 UID: 0 PID: 11650 Comm: repro3 Not tainted 6.12.0-rc5+ #92 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014 RIP: 0010:get_pat_info+0xf6/0x110 ... Call Trace: <TASK> ... untrack_pfn+0x52/0x110 unmap_single_vma+0xa6/0xe0 unmap_vmas+0x105/0x1f0 exit_mmap+0xf6/0x460 __mmput+0x4b/0x120 copy_process+0x1bf6/0x2aa0 kernel_clone+0xab/0x440 __do_sys_clone+0x66/0x90 do_syscall_64+0x95/0x180 Likely this case was missed in: d155df5 ("x86/mm/pat: clear VM_PAT if copy_p4d_range failed") ... and instead of undoing the reservation we simply cleared the VM_PAT flag. Keep the documentation of these functions in include/linux/pgtable.h, one place is more than sufficient -- we should clean that up for the other functions like track_pfn_remap/untrack_pfn separately. Fixes: d155df5 ("x86/mm/pat: clear VM_PAT if copy_p4d_range failed") Fixes: 2ab6403 ("x86: PAT: hooks in generic vm code to help archs to track pfnmap regions - v3") Reported-by: xingwei lee <xrivendell7@gmail.com> Reported-by: yuxin wang <wang1315768607@163.com> Reported-by: Marius Fleischer <fleischermarius@gmail.com> Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mm@kvack.org Link: https://lore.kernel.org/r/20250321112323.153741-1-david@redhat.com Closes: https://lore.kernel.org/lkml/CABOYnLx_dnqzpCW99G81DmOr+2UzdmZMk=T3uxwNxwz+R1RAwg@mail.gmail.com/ Closes: https://lore.kernel.org/lkml/CAJg=8jwijTP5fre8woS4JVJQ8iUA6v+iNcsOgtj9Zfpc3obDOQ@mail.gmail.com/
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Pull request for series with
subject: Improve BPF test stability (related to perf events and scheduling)
version: 2
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=618976