Re: [PATCH v1] mm: page_alloc: Add debug log in free_reserved_area for static memory

[David Hildenbrand]

On 28.09.21 12:53, Faiyaz Mohammed wrote:
> On 9/28/2021 4:09 PM, David Hildenbrand wrote:
> > On 28.09.21 11:04, Faiyaz Mohammed wrote:
> > > For INITRD and initmem memory is reserved through "memblock_reserve"
> > > during boot up but it is free via "free_reserved_area" instead
> > > of "memblock_free".
> > > For example:
> > > [    0.294848] Freeing initrd memory: 12K.
> > > [    0.696688] Freeing unused kernel memory: 4096K.
> > >
> > > To get the start and end address of the above freed memory and to account
> > > proper memblock added memblock_dbg log in "free_reserved_area".
> > > After adding log:
> > > [    0.294837] memblock_free: [0x00000083600000-0x00000083603000]
> > > free_initrd_mem+0x20/0x28
> > > [    0.294848] Freeing initrd memory: 12K.
> > > [    0.695246] memblock_free: [0x00000081600000-0x00000081a00000]
> > > free_initmem+0x70/0xc8
> > > [    0.696688] Freeing unused kernel memory: 4096K.
> > >
> > > Signed-off-by: Faiyaz Mohammed <faiyazm@xxxxxxxxxxxxxx>
> > > ---
> > >    mm/page_alloc.c | 5 +++++
> > >    1 file changed, 5 insertions(+)
> > >
> > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > > index b37435c..f85c3b2 100644
> > > --- a/mm/page_alloc.c
> > > +++ b/mm/page_alloc.c
> > > @@ -8129,6 +8129,11 @@ unsigned long free_reserved_area(void *start,
> > > void *end, int poison, const char
> > >            pr_info("Freeing %s memory: %ldK\n",
> > >                s, pages << (PAGE_SHIFT - 10));
> > >    +#ifdef CONFIG_HAVE_MEMBLOCK
> > > +        memblock_dbg("memblock_free: [%#016llx-%#016llx] %pS\n",
> > > +            __pa(start), __pa(end), (void *)_RET_IP_);
> > > +#endif
> >
> > IMHO, the "memblock_free" part is misleading. Something was allocated
> > early via memblock, then we transitioned to the buddy, now we're freeing
> > that early allocation via the buddy.
> > Yes, we're freeing the early allocation via buddy, but for proper
> memblock accounting we need this debug print.

What do you mean with "accounting" ? These are debug statements.


--
Thanks,

David / dhildenb