Messages in this thread | | | Subject | Re: [PATCH] MIPS: fix pmd_mkinvalid | From | Hongchen Zhang <> | Date | Thu, 7 Jul 2022 19:12:49 +0800 |
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On 2022/7/7 下午5:22, Thomas Bogendoerfer wrote: > On Thu, Jul 07, 2022 at 04:11:35PM +0800, Hongchen Zhang wrote: >> When a pmd entry is invalidated by pmd_mkinvalid,pmd_present should >> return true. >> So introduce a _PMD_PRESENT_INVALID_SHIFT bit to check if a pmd is >> present but invalidated by pmd_mkinvalid. > > What problem are you trying to fix ? What are the symptoms ? > >> Reported-by: kernel test robot <lkp@intel.com> > > the test robot showed problems with your last version of the patch, > which hasn't been integrated into at least the MIPS tree, so no > need to that. > > Thomas. >
Hi Thomas, The idea come from the commit: b65399f6111b(arm64/mm: Change THP helpers to comply with generic MM semantics). There is an problem now: CPU 0 CPU 1 pmdp_invalidate do_page_fault ... __handle_mm_fault is_swap_pmd == true trigger VM_BUG_ON() ? set_pmd_at the reason is that pmd_present return true,after this commit pmd_present will return false,and the VM_BUG_ON will not be triggered. Like arm64 does,we can introduce a new bit to fix this.
Thanks.
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