Re: [PATCH] sched/isolation: Postpone re-allocation of housekeeping cpumask until initcall

[Valentin Schneider]

On 10/04/26 15:27, Waiman Long wrote:
> When testing a linux-next kernel with commit 59bd1d914bb5 ("memblock:
> warn when freeing reserved memory before memory map is initialized"),
> the following warning was hit when there was a "nohz_full" kernel boot
> parameter.
>
> [    0.080911] Cannot free reserved memory because of deferred initialization of the memory map
> [    0.080911] WARNING: mm/memblock.c:904 at __free_reserved_area+0xde/0xf0, CPU#0: swapper/0/0
>   :
> [    0.080945] Call Trace:
> [    0.080947]  <TASK>
> [    0.080949]  memblock_phys_free+0xcb/0x100
> [    0.080953]  housekeeping_init+0x14c/0x170
> [    0.080957]  start_kernel+0x207/0x450
> [    0.080961]  x86_64_start_reservations+0x24/0x30
> [    0.080965]  x86_64_start_kernel+0xda/0xe0
> [    0.080967]  common_startup_64+0x13e/0x141
> [    0.080972]  </TASK>
>
> IOW, we shouldn't free memblock allocated memory so early in
> the boot process when memory map isn't fully initialized in
> deferred_init_memmap(). Fix it by adding a new housekeeping_late_init()
> helper to defer the re-allocation of the housekeeping cpumasks to when
> initcall's are being processed.
>
> Fixes: 27c3a5967f05 ("sched/isolation: Convert housekeeping cpumasks to rcu pointers")
> Signed-off-by: Waiman Long <longman@xxxxxxxxxx>

Reviewed-by: Valentin Schneider <vschneid@xxxxxxxxxx>