On 2026/10/19 12:57 PM, Michal Suchánek wrote: > On Fri, Oct 16, 2026 at 07:12:47PM +0530, Amit Machhiwal wrote: > > During early boot (early_trace_init() called from start_kernel()), > > tracing allocates initial ring buffers (temp_buffer, array_buffer, and > > snapshot_buffer) for CPU 0. Later, as secondary CPUs come online during > > smp_init(), each CPU's ring buffer is allocated via trace_rb_cpu_prepare(). > > > > Before attempting page allocation, __rb_allocate_pages() performs a > > heuristic check using si_mem_available() to return early with -ENOMEM if > > memory appears insufficient. > >
<snip> > > kernel/trace/ring_buffer.c | 14 ++++++++++++++ > > 1 file changed, 14 insertions(+) > > > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > > index 04bb94c29f58..aa877a272c89 100644 > > --- a/kernel/trace/ring_buffer.c > > +++ b/kernel/trace/ring_buffer.c > > @@ -2452,10 +2452,24 @@ static int __rb_allocate_pages(struct > > ring_buffer_per_cpu *cpu_buffer, > > * memory. It may not be accurate. But we don't care, we just want > > * to prevent doing any allocation when it is obvious that it is > > * not going to succeed. > > + * > > + * With CONFIG_DEFERRED_STRUCT_PAGE_INIT, NR_FREE_PAGES only reflects > > + * the initial non-deferred pool during early boot and throughout SMP > > + * bring-up (smp_init() runs before page_alloc_init_late() completes > > + * deferred initialization). si_mem_available() returns a false negative > > + * across this entire window while actual allocations succeed by growing > > + * the zone on demand via deferred_grow_zone(). Only re-enable the check > > + * from SYSTEM_FREEING_INITMEM onward, after page_alloc_init_late() has > > + * finished and si_mem_available() is accurate. > > */ > > i = si_mem_available(); > > +#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT > > + if (system_state >= SYSTEM_FREEING_INITMEM && i < nr_pages) > > + return -ENOMEM; > > +#else > > if (i < nr_pages) > > return -ENOMEM; > > +#endif > > > > /* > > * If a user thread allocates too much, and si_mem_available() > > > > base-commit: 2f2f7eeef8b0a1a9b9ca998231419873ccae8d4e > > Hello, > > due to other conflicting changes this no longer applies. > > Will you send a rebase? Hi Michal, Thanks for checking and notifying. I'll look into it and send a v3 as needed. Thanks, Amit
