Messages in this thread | | | Date | Fri, 21 Jul 2023 17:18:58 +0200 | Subject | Re: [PATCH] riscv: mm: Fixup spurious fault of kernel vaddr | From | Alexandre Ghiti <> |
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On 21/07/2023 16:51, guoren@kernel.org wrote: > From: Guo Ren <guoren@linux.alibaba.com> > > RISC-V specification permits the caching of PTEs whose V (Valid) > bit is clear. Operating systems must be written to cope with this > possibility, but implementers are reminded that eagerly caching > invalid PTEs will reduce performance by causing additional page > faults. > > So we must keep vmalloc_fault for the spurious page faults of kernel > virtual address from an OoO machine. > > Signed-off-by: Guo Ren <guoren@linux.alibaba.com> > Signed-off-by: Guo Ren <guoren@kernel.org> > --- > arch/riscv/mm/fault.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c > index 85165fe438d8..f662c9eae7d4 100644 > --- a/arch/riscv/mm/fault.c > +++ b/arch/riscv/mm/fault.c > @@ -258,8 +258,7 @@ void handle_page_fault(struct pt_regs *regs) > * only copy the information from the master page table, > * nothing more. > */ > - if ((!IS_ENABLED(CONFIG_MMU) || !IS_ENABLED(CONFIG_64BIT)) && > - unlikely(addr >= VMALLOC_START && addr < VMALLOC_END)) { > + if (unlikely(addr >= TASK_SIZE)) { > vmalloc_fault(regs, code, addr); > return; > }
Can you share what you are trying to fix here?
I have a fix (that's currently running our CI) for commit 7d3332be011e ("riscv: mm: Pre-allocate PGD entries for vmalloc/modules area") that implements flush_cache_vmap() since we lost the vmalloc_fault.
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