Re: [Patch v3] mm/memblock: remove empty dummy entry

[Wei Yang <richard.weiyang@gmail.com>]

On Thu, Jun 20, 2024 at 02:58:17PM -0700, Guenter Roeck wrote:
>Hi,
>
>On Fri, Apr 05, 2024 at 01:58:21AM +0000, Wei Yang wrote:
>> The dummy entry is introduced in the initial implementation of lmb in
>> commit 7c8c6b9776fb ("powerpc: Merge lmb.c and make MM initialization
>> use it.").
>> 
>> As the comment says the empty dummy entry is to simplify the code.
>> 
>> 	/* Create a dummy zero size LMB which will get coalesced away later.
>>          * This simplifies the lmb_add() code below...
>>          */
>> 
>> While current code is reimplemented by Tejun in commit 784656f9c680
>> ("memblock: Reimplement memblock_add_region()"). This empty dummy entry
>> seems not benefit the code any more.
>> 
>> Let's remove it.
>> 
>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>> CC: Paul Mackerras <paulus@ozlabs.org>
>> CC: Tejun Heo <tj@kernel.org>
>> CC: Mike Rapoport <rppt@kernel.org>
>> 
>
>With this patch in linux-next, all microblaze qemu images fail to boot. Reverting it
>fixes the problem.
>
>Bisect log is attached for reference.
>

Also, would you mind add kernel parameter memblock=debug and give me the log?

>Guenter
>
>---
># bad: [2102cb0d050d34d50b9642a3a50861787527e922] Add linux-next specific files for 20240619
># good: [6ba59ff4227927d3a8530fc2973b80e94b54d58f] Linux 6.10-rc4
>git bisect start 'HEAD' 'v6.10-rc4'
># good: [a8fa5261ec87d5aafd3211548d93008d5739457d] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git
>git bisect good a8fa5261ec87d5aafd3211548d93008d5739457d
># good: [ee551f4db89753511a399b808db75654facec7c8] Merge branch 'for-linux-next' of https://gitlab.freedesktop.org/drm/i915/kernel
>git bisect good ee551f4db89753511a399b808db75654facec7c8
># good: [ec3557f4b791d72d93bfb69702d441d2c9f8cd0d] Merge branch 'next' of git://git.kernel.org/pub/scm/virt/kvm/kvm.git
>git bisect good ec3557f4b791d72d93bfb69702d441d2c9f8cd0d
># good: [48d51b3acbb237074014d498d76ea6b6ce5aed69] Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/phy/linux-phy.git
>git bisect good 48d51b3acbb237074014d498d76ea6b6ce5aed69
># good: [59972b98583cd97febf9ecc576a706a7c5046278] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl.git
>git bisect good 59972b98583cd97febf9ecc576a706a7c5046278
># good: [49aa15d761ce8976bb131f06886e89bd10cdb9fd] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching
>git bisect good 49aa15d761ce8976bb131f06886e89bd10cdb9fd
># bad: [129b9b07cd69885a804319c3fac82ef79e012e07] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock.git
>git bisect bad 129b9b07cd69885a804319c3fac82ef79e012e07
># good: [344db92cbecc8da1f58d559926c61ceb72e72a03] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/srini/nvmem.git
>git bisect good 344db92cbecc8da1f58d559926c61ceb72e72a03
># bad: [ce8ebb95439459f7e24b02c6943e278f46d2d328] mm/mm_init.c: get the highest zone directly
>git bisect bad ce8ebb95439459f7e24b02c6943e278f46d2d328
># bad: [1a879671bdfd14698a839f30de8e6d76e1e858fd] memblock tests: add memblock_overlaps_region_checks
>git bisect bad 1a879671bdfd14698a839f30de8e6d76e1e858fd
># bad: [3d3165193776ddacf59f101f0fa05cfab9f1a9ba] memblock tests: add memblock_reserve_all_locations_check()
>git bisect bad 3d3165193776ddacf59f101f0fa05cfab9f1a9ba
># bad: [721f4a6526daafca15634f30c9865e880da3e1d1] mm/memblock: remove empty dummy entry
>git bisect bad 721f4a6526daafca15634f30c9865e880da3e1d1
># first bad commit: [721f4a6526daafca15634f30c9865e880da3e1d1] mm/memblock: remove empty dummy entry

-- 
Wei Yang
Help you, Help me