Re: [Crash-utility] [PATCH] arm64: handle 1GB block

Hi Lianbo >> >> With enough continuous physical memory we can have 1GB block. This have >> been seen only in linear mapping region in kernel space. I have only >> verified this for VM_L3_4K. >> >> reference: alloc_init_pud(), use_1G_block() [arch/arm64/mm/mmu.c] >> > For this situation, do you know how to reproduce it easily? Can you share > your steps in detail? I can try, one requirement is that you have memory aligned at 1 GB and size is at least 1 GB. Lets assume we have vmcore with physical memory at 0x100000000 (1 GB aligned) with size at least 1 GB. Then from crash we could do:

crash> ptov 100000000 VIRTUAL PHYSICAL ffffffe900000000 100000000 crash> vtop ffffffe900000000 VIRTUAL PHYSICAL ffffffe900000000 100000000 PAGE DIRECTORY: ffffff990f66c000 PGD: ffffff990f66cd20 => 68000100000711 PAGE: 100000000 (1GB) PTE PHYSICAL FLAGS 68000100000711 100000000 (VALID|SHARED|AF|PXN|UXN) PAGE PHYSICAL MAPPING INDEX CNT FLAGS ffffffbfa4000000 100000000 ffffffe97de59090 fe 2 20054 uptodate,lru,workingset,mappedtodisk I hope that helps. Yes, it certainly helps.

Regards Johan > BTW: I did the test, but I didn't enter into the kernel code path because > that condition was not met. > > # dmesg|grep -i huge > [ 0.000000] Kernel command line: BOOT_IMAGE=(hd0,gpt2)/vmlinuz-5.12.0-rc7+ root=/dev/mapper/rhel_gigabyte--r120--20-root ro arm->smmu.disable_bypass=n initcall_blacklist=gtdt_sbsa_gwdt_init iommu.passthrough=1 crashkernel=512M hugepagesz=1G hugepages=6 >debug_pagealloc=on rd.lvm.lv=rhel_gigabyte-r120-20/root rd.lvm.lv=rhel_gigabyte-r120-20/swap > [ 2.620634] HugeTLB registered 1.00 GiB page size, pre-allocated 6 pages > > Thanks. > Lianbo