Hi Ard, On Wed, Nov 7, 2018 at 7:46 PM Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote: > > This series addresses the kexec/kdump crash on arm64 system with many CPUs > that was reported by Bhupesh. > > Patch #1 fixes the actual crash, but may result in memblock_reserve() to > fail. This is fixed in patch #4, where the point that the persistent > reservations are applied is moved to after memblock_allow_resize() has > been called. > > Patches #2 and #3 contain some minor preparatory changes that are > required on ARM to ensure that efi_apply_persistent_mem_reservations() > can be called at some point (i.e., when memblock resizing is already > permitted and early memremap() is still usable) > > Patches #5 and #6 optimize the EFI persistent memreserve infrastructure > so that fewer memblock reservations are required. > > Changes since v1: > - Russell pointed out that switching to ordinary memremap() was not > possible this early, and so I refactored the ARM early boot code > slightly so that we can keep using early_memremap(). > > Ard Biesheuvel (6): > arm64: memblock: don't permit memblock resizing until linear mapping > is up > ARM: mm: permit memblock resizing right after mapping the linear > region > ARM: mm: permit early_memremap() to be used in paging_init() > efi/arm: defer persistent reservations until after paging_init() > efi: permit multiple entries in persistent memreserve data structure > efi: reduce the amount of memblock reservations for persistent > allocations > > arch/arm/kernel/setup.c | 2 - > arch/arm/mm/init.c | 1 - > arch/arm/mm/mmu.c | 5 ++ > arch/arm64/kernel/setup.c | 1 + > arch/arm64/mm/init.c | 2 - > arch/arm64/mm/mmu.c | 2 + > drivers/firmware/efi/efi.c | 59 ++++++++++++++------ > drivers/firmware/efi/libstub/arm-stub.c | 2 +- > include/linux/efi.h | 23 +++++++- > 9 files changed, 72 insertions(+), 25 deletions(-) > > -- > 2.19.1 > I did some quick checks (as I just returned from my holidays and got hold of the hardware just now) and I haven't had the opportunity to look closely at the entire patch set, but it looks like a step in the right direction especially as we try to have fewer memblock reservations (I will have a closer look at the patchset perhaps over the weekend). I tested this on the hardware (with 224 CPUs) where I was seeing the crash initially and kdump seems to work fine on the same. Here are some kdump kernel logs with 'memblock=debug' set in bootargs: [ 0.000000] memblock_reserve: [0x00000000e2e02e18-0x00000000e2e02e4f] efi_mem_reserve+0x3c/0x54 [ 0.000000] memblock_reserve: [0x00000000dac70000-0x00000000dac7ffff] efi_init+0xc4/0x17c [ 0.000000] memblock_remove: [0x0001000000000000-0x0000fffffffffffe] arm64_memblock_init+0x6c/0x418 [ 0.000000] memblock_remove: [0x0000800080000000-0x000080007ffffffe] arm64_memblock_init+0xac/0x418 [ 0.0001dd0000-0x00000000a2cfffff] arm64_memblock_init+0x184/0x418 [ 0.000000] memblock_add: [0x00000000a1dd0000-0x00000000a2cfffff] arm64_memblock_init+0x190/0x418 [ 0.000000] memblock_reserve: [0x00000000a1dd0000-0x00000000a2cfffff] arm64_memblock_init+0x19c/0x418 [ 0.000000] memblock_reserve: [0x00000000a0080000-0x00000000a1dcffff] arm64_memblock_init+0x1f8/0x418 [ 0.000000] memblock_reserve: [0x00000000a1dd0000-0x00000000a2cfb402] 0.000000] memblock_reserve: [0x00000000bfff0000-0x00000000bfff33ff] arm64_memblock_init+0x3b4/0x418 [ 0.000000] Reserving 13KB of memory at 0xbfff0000 for elfcorehdr [ 0.000000] memblock_reserve: [0x00000000bffe0000-0x00000000bffeffff] memblock_alloc_base_nid+0x70/0x8c [ 0.000000] memblock_reserve: [0x00000000bffd0000-0x00000000bffdffff] memblock_alloc_base_nid+0x70/0x8c [ 0.000000] memblock_reserve: [0x00000000bffc0se_nid+0x70/0x8c [ 0.000000] memblock_reserve: [0x00000000bffb0000-0x00000000bffbffff] memblock_alloc_base_nid+0x70/0x8c [ 0.000000] memblock_free: [0x00000000a1d80000-0x00000000a1dcffff] paging_init+0x6d4/0x6fc [ 0.000000] memblock_reserve: [0x00000000ddab9e18-0x00000000ddab9e27] efi_apply_persistent_mem_reservations+0x8c/0xbc So, things look great so far. So, please feel free to add: Tested-by: Bhupesh Sharma <bhsharma@xxxxxxxxxx> Thanks, Bhupesh
