ci: Doc ASLR workaround for sanitizer tasks #33674

1. 
   maflcko commented at 7:15 am on October 22, 2025: member

   Fixes https://github.com/bitcoin/bitcoin/issues/30674
2. ci: Doc ASLR workaround for sanitizer tasks fa0e36156c
3. DrahtBot added the label Tests on Oct 22, 2025
4. 
   DrahtBot commented at 7:15 am on October 22, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33674.

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5. maflcko requested review from Sjors on Oct 22, 2025
6. 
   fanquake commented at 7:18 am on October 23, 2025: member

   ACK fa0e36156cba535846ae2ecfaaa554d7f14fcdfd
7. fanquake merged this on Oct 23, 2025
8. fanquake closed this on Oct 23, 2025

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9. maflcko deleted the branch on Oct 23, 2025
10. in ci/README.md:28 in fa0e36156c

    19@@ -20,6 +20,14 @@ requires `bash`, `docker`, and `python3` to be installed. To run on different ar
    20 sudo apt install bash docker.io python3 qemu-user-static
    21 ```
    22 
    23+For some sanitizer builds, the kernel's address-space layout randomization
    24+(ASLR) entropy can cause sanitizer shadow memory mappings to fail. When running
    25+the CI locally you may need to reduce that entropy by running:
    26+
    27+```
    28+sudo sysctl -w vm.mmap_rnd_bits=28
    

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    Sjors commented at 10:40 am on October 24, 2025:

    What does -w do?

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    Sjors commented at 10:41 am on October 24, 2025:

    0       -w, --write
    1              Force all arguments to be write arguments and print an error if they cannot be parsed this way.
    

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    maflcko commented at 12:54 pm on October 24, 2025:

    Yeah, seems preferable to always use the long option name for self-documenting code to avoid confusion. Can be changed in a follow-up, as this is merged.
11. 
    Sjors commented at 10:41 am on October 24, 2025: member

    Post merge ACK

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maflcko DrahtBot fanquake Sjors

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