Re: [Crash-utility] [PATCH] ppc64: do page traversal if vmemmap_list not populated

On Wed, Sep 20, 2023 at 7:17 PM Aditya Gupta <adityag(a)linux.ibm.com&gt; wrote: > Hello lijiang, > > On Wed, Sep 20, 2023 at 10:21:18AM +0800, lijiang wrote: > > On Tue, Sep 19, 2023 at 2:23 PM Aditya Gupta <adityag(a)linux.ibm.com&gt; > wrote: > > > > > Hello lijiang, > > > > > > On Mon, Sep 18, 2023 at 07:34:04PM +0800, lijiang wrote: > > > > Hi, Aditya > > > > Thank you for the patch. > > > > > > > > ... > > > > > > > > Test kernel commit: ce9ecca0238b ("Linux 6.6-rc2") > > > > > > > > # ./crash /home/linux/vmlinux > > > > > > Thanks for testing it. > > > > > > This issue occurs only in case of Radix MMU. > > > > > > Overall, these are all the requirements: > > > 1. Upstream linux (master branch) (your commit will also work, > > > ce9ecca0238b) > > > 2. 'CONFIG_PPC_BOOK3S_64' should be 'y' in kernel config (this should > be > > > there > > > in default configs) > > > > > > > # grep "CONFIG_PPC_BOOK3S_64" /home/linux/.config > > CONFIG_PPC_BOOK3S_64=y > > > > 3. Check in dmesg of the crashed kernel, if it prints 'hash-mmu' or > > > 'radix-mmu'. It should be 'radix-mmu'. > > > > > > > > # dmesg|grep mmu > > [ 0.000000] hash-mmu: Page sizes from device-tree: > > [ 0.000000] hash-mmu: base_shift=12: shift=12, sllp=0x0000, > > avpnm=0x00000000, tlbiel=1, penc=0 > > [ 0.000000] hash-mmu: base_shift=12: shift=16, sllp=0x0000, > > avpnm=0x00000000, tlbiel=1, penc=7 > > [ 0.000000] hash-mmu: base_shift=12: shift=24, sllp=0x0000, > > avpnm=0x00000000, tlbiel=1, penc=56 > > [ 0.000000] hash-mmu: base_shift=16: shift=16, sllp=0x0110, > > avpnm=0x00000000, tlbiel=1, penc=1 > > [ 0.000000] hash-mmu: base_shift=16: shift=24, sllp=0x0110, > > avpnm=0x00000000, tlbiel=1, penc=8 > > [ 0.000000] hash-mmu: base_shift=24: shift=24, sllp=0x0100, > > avpnm=0x00000001, tlbiel=0, penc=0 > > [ 0.000000] hash-mmu: base_shift=34: shift=34, sllp=0x0120, > > avpnm=0x000007ff, tlbiel=0, penc=3 > > [ 0.000000] hash-mmu: Initializing hash mmu with SLB > > [ 0.000000] mmu_features = 0xfc006e01 > > [ 0.000000] hash-mmu: ppc64_pft_size = 0x1b > > [ 0.000000] hash-mmu: htab_hash_mask = 0xfffff > > > > This seems to using Hash MMU, hence the error doesn't come up. > Since vmemmap_list is NOT empty in case of Hash MMU, so crash works as > expected. > > Thank you for the explanation, Aditya. > Can you try it on a system with Radix MMU ? (Rainier/Denali systems might > have > that by default) > > I'm afraid I don't have such machines with Radix MMU. Looks like I can not test it, let's reback to the discussion of patches.