Messages in this thread Patch in this message | | | Date | Wed, 27 Sep 2017 16:50:08 +0100 | From | Will Deacon <> | Subject | Re: ARM64: kernel panics in DABT in sys_msync path |
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On Tue, Sep 26, 2017 at 06:31:12PM +0100, Will Deacon wrote: > On Tue, Sep 26, 2017 at 08:23:35AM -0600, Ruigrok, Richard wrote: > > On 9/26/2017 4:23 AM, Will Deacon wrote: > > > On Mon, Sep 25, 2017 at 01:54:57PM -0600, Ruigrok, Richard wrote: > > >> I also found this issue with kernels from 4.11 through 4.13. In my tests, I > > >> found that it reproduces only with 4K page and Transparent Huge Pages. With 64K > > >> page I was not able to reproduce. RH also reported it here: https:// > > >> bugzilla.redhat.com/show_bug.cgi?id=1491504 Linaro reported on the RPK kernel > > >> (4.12) on Centriq2400 and ThunderX > > >> > > >> > > >> https://bugs.linaro.org/show_bug.cgi?id=3191 > > >> > > >> https://bugs.linaro.org/show_bug.cgi?id=3068. > > > These two aren't the same bug (that's a forward progress issue that we're > > > currently working on). I don't have permission to look at the redhat one, > > > but is it just an RCU stall or actually the Oops reported by Yury? > > > > > >> I was able to bisect down to a specific commit. > > > I think we're chasing two different things here, so not sure I trust the > > > bisect! > > > > > The RCU stall is side effect. The issue I'm seeing has the same stack > > trace and same stimulus (rwtest). Following are the details. > > FWIW, I think I've worked out what's going on here and I should have a patch > tomorrow.
Diff below. I'm going to follow up with a separate thread about this, because the proper fix is going to be invasive. I'll keep you on cc.
Out of curiosity: what version of GCC are you using to compile the kernel?
Will
--->8
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index bc4e92337d16..b46e54c2399b 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -401,7 +401,7 @@ static inline phys_addr_t pmd_page_paddr(pmd_t pmd) /* Find an entry in the third-level page table. */ #define pte_index(addr) (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) -#define pte_offset_phys(dir,addr) (pmd_page_paddr(*(dir)) + pte_index(addr) * sizeof(pte_t)) +#define pte_offset_phys(dir,addr) (pmd_page_paddr(READ_ONCE(*(dir))) + pte_index(addr) * sizeof(pte_t)) #define pte_offset_kernel(dir,addr) ((pte_t *)__va(pte_offset_phys((dir), (addr)))) #define pte_offset_map(dir,addr) pte_offset_kernel((dir), (addr))
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