On 8 November 2018 at 20:13, Bhupesh Sharma <bhsharma@xxxxxxxxxx> wrote: > 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!
