On Wed, Mar 28, 2018 at 05:49:23PM +0800, Jia He wrote: > > >On 3/28/2018 5:18 PM, Wei Yang Wrote: >> Oops, I should reply this thread. Forget about the reply on another thread. >> >> On Sun, Mar 25, 2018 at 08:02:15PM -0700, Jia He wrote: >> > Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns >> > where possible") optimized the loop in memmap_init_zone(). But it causes >> > possible panic bug. So Daniel Vacek reverted it later. >> > >> Why this has a bug? Do you have some link about it? >> >> If the audience could know the potential risk, it would be helpful to review >> the code and decide whether to take it back. >Hi Wei >Paul firstly submit a commit b92df1de5 to improve the loop in >memmap_init_zone. >And Daniel tried to fix a bug_on panic issue on X86 in commit 864b75f9d6b >because >there is evidence that this bug_on was caused by b92df1de5 [1]. > >But things didn't get better, 864b75f9d6b caused booting hang issue on >arm{64} [2] >So maintainer decided to reverted both b92df1de5 and 864b75f9d6b > >[1] https://patchwork.kernel.org/patch/10251145/ >[2] https://lkml.org/lkml/2018/3/14/469 I took some time to look into the discussion, while the root cause seems not clear now? -- Wei Yang Help you, Help me