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Date:   Wed, 11 Nov 2020 14:28:43 +0200
From:   Mike Rapoport <rppt@kernel.org>
To:     Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        vinmenon@codeaurora.org
Subject: Re: [PATCH] mm: memblock: add more debug logs
Message-ID: <20201111122843.GH4758@kernel.org>
References: <1605010798-17545-1-git-send-email-faiyazm@codeaurora.org>
 <20201110181605.GC4758@kernel.org>
 <f1e3c3c8-ed4f-9283-e221-7faec10fdd8d@codeaurora.org>
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On Wed, Nov 11, 2020 at 01:30:40PM +0530, Faiyaz Mohammed wrote:
> 
> On 11/10/2020 11:46 PM, Mike Rapoport wrote:
> > Hi,
> > 
> > On Tue, Nov 10, 2020 at 05:49:58PM +0530, Faiyaz Mohammed wrote:
> > > Exact caller of memblock_phys_alloc_range is not available with
> > > "memblock=debug". Below information is not enough for memory accounting.
> > > for example:
> > > [    0.000000] memblock_reserve: [0x000000023fc6b000-0x000000023fc6bfff] memblock_alloc_range_nid+0xc0/0x188
> > > 
> > > To enhance the memblock_dbg information or to get the exact owner of the
> > > memblock_reserve, add debug logs in memblock_phys_alloc_range function.
> > Why would you want to use memblock=debug for memory accounting or for
> > tracking of the owners of the reserved memory?

> We do memblock reserved accounting to track owners to know size of memory
> allocated by different drivers/owners through memblock_reserve, which help
> in comparing different kernel version and in optimizations.

I'd suggest to update the commit messaget to somthing like:

It is usefull to know the exact caller of memblock_phys_alloc_range() to
track early memory reservations during developement. 

Currently, when memblock debugging is enabled, the allocations done with
memblock_phys_alloc_range() are only reported at memblock_reserve():

[    0.000000] memblock_reserve: [0x000000023fc6b000-0x000000023fc6bfff] memblock_alloc_range_nid+0xc0/0x188

Add memblock_dbg() to memblock_phys_alloc_range() to get details about
its usage.

For example:

[    0.000000] memblock_phys_alloc_range: 4096 bytes align=0x1000 from=0x0000000000000000 max_addr=0x0000000000000000 early_pgtable_alloc+0x24/0x178
[    0.000000] memblock_reserve: [0x000000023fc6b000-0x000000023fc6bfff] memblock_alloc_range_nid+0xc0/0x188

> > > After adding logs:
> > > [    0.000000] memblock_phys_alloc_range: 4096 bytes align=0x1000 from=0x0000000000000000 max_addr=0x0000000000000000 early_pgtable_alloc+0x24/0x178
> > > [    0.000000] memblock_reserve: [0x000000023fc6b000-0x000000023fc6bfff] memblock_alloc_range_nid+0xc0/0x188
> > > 
> > > Signed-off-by: Faiyaz Mohammed <faiyazm@codeaurora.org>
> > > ---
> > >   mm/memblock.c | 3 +++
> > >   1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/mm/memblock.c b/mm/memblock.c
> > > index 049df41..f65af9f 100644
> > > --- a/mm/memblock.c
> > > +++ b/mm/memblock.c
> > > @@ -1419,6 +1419,9 @@ phys_addr_t __init memblock_phys_alloc_range(phys_addr_t size,
> > >   					     phys_addr_t start,
> > >   					     phys_addr_t end)
> > >   {
> > > +	memblock_dbg("%s: %llu bytes align=0x%llx from=%pa max_addr=%pa %pS\n",
> > > +			__func__, (u64)size, (u64)align, &start, &end,
> > > +			(void *)_RET_IP_);
> > >   	return memblock_alloc_range_nid(size, align, start, end, NUMA_NO_NODE,
> > >   					false);
> > >   }
> > > -- 
> > > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
> > > member of the Code Aurora Forum, hosted by The Linux Foundation
> > > 

-- 
Sincerely yours,
Mike.