Re: [PATCH 4/8] mm/vmalloc: Remove cond_resched() in vm_area_alloc_pages()

[Uladzislau Rezki]

On Thu, Aug 07, 2025 at 01:22:36PM +0200, Michal Hocko wrote:
> On Thu 07-08-25 09:58:06, Uladzislau Rezki wrote:
> > The vm_area_alloc_pages() function uses cond_resched() to yield the
> > CPU during potentially long-running loops. However, these loops are
> > not considered long-running under normal conditions.
> 
> To be more precise they can take long if they dive into the page
> allocator but that already involves cond_rescheds where appropriate so
> these are not needed in fact.
> 
> > In non-blocking
> > contexts, calling cond_resched() is inappropriate also.
> > 
> > Remove these calls to ensure correctness for blocking/non-blocking
> > contexts. This also simplifies the code path. In fact, a slow path
> > of page allocator already includes reschedule points to mitigate
> > latency.
> > 
> > This patch was tested for !CONFIG_PREEMPT kernel and with large
> > allocation chunks(~1GB), without triggering any "BUG: soft lockup"
> > warnings.
> > 
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
> 
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> 
> Thanks!
>
Updated the commit message. Right, it can take long time.

Thank you!

--
Uladzislau Rezki