On 09/25/2019 08:43 AM, Andrew Morton wrote: > On Mon, 23 Sep 2019 11:16:38 +0530 Anshuman Khandual <anshuman.khandual@xxxxxxx> wrote: > >> >> >> On 09/16/2019 11:17 AM, Anshuman Khandual wrote: >>> In add_memory_resource() the memory range to be hot added first gets into >>> the memblock via memblock_add() before arch_add_memory() is called on it. >>> Reverse sequence should be followed during memory hot removal which already >>> is being followed in add_memory_resource() error path. This now ensures >>> required re-order between memblock_[free|remove]() and arch_remove_memory() >>> during memory hot-remove. >>> >>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >>> Cc: Oscar Salvador <osalvador@xxxxxxx> >>> Cc: Michal Hocko <mhocko@xxxxxxxx> >>> Cc: David Hildenbrand <david@xxxxxxxxxx> >>> Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> >>> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> >>> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> >>> --- >>> Original patch https://lkml.org/lkml/2019/9/3/327 >>> >>> Memory hot remove now works on arm64 without this because a recent commit >>> 60bb462fc7ad ("drivers/base/node.c: simplify unregister_memory_block_under_nodes()"). >>> >>> David mentioned that re-ordering should still make sense for consistency >>> purpose (removing stuff in the reverse order they were added). This patch >>> is now detached from arm64 hot-remove series. >>> >>> https://lkml.org/lkml/2019/9/3/326 >> >> ... >> >> Hello Andrew, >> >> Any feedbacks on this, does it look okay ? >> > > Well. I'd parked this for 5.4-rc1 processing because it looked like a > cleanup. This does not fix a serious problem. It just removes an inconsistency while freeing resources during memory hot remove which for now does not pose a real problem. > > But waaaay down below the ^---$ line I see "Memory hot remove now works > on arm64". Am I correct in believing that 60bb462fc7ad broke arm64 mem > hot remove? And that this patch fixes a serious regression? If so, No. [Proposed] arm64 memory hot remove series does not anymore depend on this particular patch because 60bb462fc7ad has already solved the problem. > that should have been right there in the patch title and changelog! V2 (https://patchwork.kernel.org/patch/11159939/) for this patch makes it very clear in it's commit message. - Anshuman
