Messages in this thread Patch in this message | | | Date | Tue, 10 Jan 2023 07:59:47 +0100 | From | Andrew Jones <> | Subject | Re: [PATCH v2 2/3] RISC-V: mm: Enable huge page support to kernel_page_present() function |
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On Tue, Jan 10, 2023 at 06:45:19AM +0000, JeeHeng Sia wrote: > > > > -----Original Message----- > > From: Andrew Jones <ajones@ventanamicro.com> > > Sent: Monday, 9 January, 2023 10:45 PM > > To: JeeHeng Sia <jeeheng.sia@starfivetech.com> > > Cc: paul.walmsley@sifive.com; palmer@dabbelt.com; > > aou@eecs.berkeley.edu; linux-riscv@lists.infradead.org; linux- > > kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; > > Mason Huo <mason.huo@starfivetech.com> > > Subject: Re: [PATCH v2 2/3] RISC-V: mm: Enable huge page support to > > kernel_page_present() function > > > > On Mon, Jan 09, 2023 at 02:24:06PM +0800, Sia Jee Heng wrote: > > > Currently kernel_page_present() function doesn't support huge page > > > detection causes the function to mistakenly return false to the > > > hibernation core. > > > > > > Add huge page detection to the function to solve the problem. > > > > > > Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com> > > > Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com> > > > Reviewed-by: Mason Huo <mason.huo@starfivetech.com> > > > --- > > > arch/riscv/mm/pageattr.c | 6 ++++++ > > > 1 file changed, 6 insertions(+) > > > > > > diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c > > > index 86c56616e5de..73fdec8c0a72 100644 > > > --- a/arch/riscv/mm/pageattr.c > > > +++ b/arch/riscv/mm/pageattr.c > > > @@ -221,14 +221,20 @@ bool kernel_page_present(struct page *page) > > > p4d = p4d_offset(pgd, addr); > > > if (!p4d_present(*p4d)) > > > return false; > > > + if (p4d_leaf(*pud)) > > ^ p4d > > > > I guess you got lucky with the stack garbage in your testing. > You are right. But the reason it is added here is because kernel page table walk is checking for the p4d_leaf as well. > For example: walk_p4d_range() in the mm/pagewalk.c. So, I just trying to make it consistent to the Kernel page table walk mechanism. > Should I remove it?
The only thing I see wrong with it is the use of the uninitialized pointer. Just change 'pud' to 'p4d'.
Thanks, drew
> > > > > + return true; > > > > > > pud = pud_offset(p4d, addr); > > > if (!pud_present(*pud)) > > > return false; > > > + if (pud_leaf(*pud)) > > > + return true; > > > > > > pmd = pmd_offset(pud, addr); > > > if (!pmd_present(*pmd)) > > > return false; > > > + if (pmd_leaf(*pmd)) > > > + return true; > > > > > > pte = pte_offset_kernel(pmd, addr); > > > return pte_present(*pte); > > > -- > > > 2.34.1 > > > > > > > Thanks, > > drew
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