Messages in this thread | | | Date | Fri, 10 Feb 2023 18:15:22 +0100 | Subject | Re: [PATCH v10 2/5] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity() | From | "Linux kernel regression tracking (#update)" <> |
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[TLDR: This mail in primarily relevant for Linux kernel regression tracking. There afaics is a fix for the regression discussed in this thread, but it did not use a Link: tag to point to the report, as Linus and the documentation call for. Things happen, no worries -- but it forces me to write this mail to make the regression tracking bot aware of the fix. See link in footer if these mails annoy you.]
On 26.01.23 13:52, Linux kernel regression tracking (#adding) wrote: > On 17.01.23 17:08, Will Deacon wrote: >> >> On Thu, Sep 22, 2022 at 02:00:38PM -0400, Waiman Long wrote: >>> The user_cpus_ptr field is added by commit b90ca8badbd1 ("sched: >>> Introduce task_struct::user_cpus_ptr to track requested affinity"). It >>> is currently used only by arm64 arch due to possible asymmetric CPU >>> setup. This patch extends its usage to save user provided cpumask >>> when sched_setaffinity() is called for all arches. With this patch >>> applied, user_cpus_ptr, once allocated after a successful call to >>> sched_setaffinity(), will only be freed when the task exits. >> [...] >> We've tracked this down as the cause of an arm64 regression in Android and I've >> reproduced the issue with mainline. >> >> Basically, if an arm64 system is booted with "allow_mismatched_32bit_el0" on >> the command-line, then the arch code will (amongst other things) call >> force_compatible_cpus_allowed_ptr() and relax_compatible_cpus_allowed_ptr() >> when exec()'ing a 32-bit or a 64-bit task respectively. >> [...] > > Thanks for the report. To be sure the issue doesn't fall through the > cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression > tracking bot: > > #regzbot ^introduced 8f9ea86fdf99
#regzbot fix: 3fb906e7fabbb5b76c3c #regzbot ignore-activity
Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat) -- Everything you wanna know about Linux kernel regression tracking: https://linux-regtracking.leemhuis.info/about/#tldr That page also explains what to do if mails like this annoy you.
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