Failure after v6.1-rc4-9-g9ed2b4616d4e: arm64/mm: Drop redundant BUG_ON(!pgtable_alloc):

Results changed to -10 # build_abe binutils: -9 # build_abe stage1: -5 # build_abe qemu: -2 # linux_n_obj: 629 # linux build successful: all # First few build errors in logs:

from -10 # build_abe binutils: -9 # build_abe stage1: -5 # build_abe qemu: -2 # linux_n_obj: 629 # linux build successful: all # linux boot successful: boot

THIS IS THE END OF INTERESTING STUFF. BELOW ARE LINKS TO BUILDS, REPRODUCTION INSTRUCTIONS, AND THE RAW COMMIT.

For latest status see comments in https://linaro.atlassian.net/browse/GNU-681 . Status of v6.1-rc4-9-g9ed2b4616d4e commit for tcwg_kernel: commit 9ed2b4616d4e846ece2a04cb5007ce1d1bd9e3f3 Author: Anshuman Khandual anshuman.khandual@arm.com Date: Fri Nov 18 11:01:02 2022 +0530

arm64/mm: Drop redundant BUG_ON(!pgtable_alloc)

__create_pgd_mapping_locked() expects a page allocator used while mapping a virtual range. This page allocator function propagates down the call chain, while building intermediate levels in the page table. Passed page allocator is a necessary ingredient required to build the page table but its presence can be asserted just once in the very beginning rather than in all the down stream functions. This consolidates BUG_ON(!pgtable_alloc) checks just in a single place i.e __create_pgd_mapping_locked().

Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Andrew Morton akpm@linux-foundation.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual anshuman.khandual@arm.com Acked-by: Mark Rutland mark.rutland@arm.com Link: https://lore.kernel.org/r/20221118053102.500216-1-anshuman.khandual@arm.com Signed-off-by: Will Deacon will@kernel.org * gnu-release-aarch64-next-allnoconfig ** Failure after v6.1-rc4-9-g9ed2b4616d4e: arm64/mm: Drop redundant BUG_ON(!pgtable_alloc): ** https://ci.linaro.org/job/tcwg_kernel-gnu-build-gnu-release-aarch64-next-all...

Bad build: https://ci.linaro.org/job/tcwg_kernel-gnu-build-gnu-release-aarch64-next-all... Good build: https://ci.linaro.org/job/tcwg_kernel-gnu-build-gnu-release-aarch64-next-all...

Reproduce current build: <cut> mkdir -p investigate-linux-9ed2b4616d4e846ece2a04cb5007ce1d1bd9e3f3 cd investigate-linux-9ed2b4616d4e846ece2a04cb5007ce1d1bd9e3f3

# Fetch scripts git clone https://git.linaro.org/toolchain/jenkins-scripts

# Fetch manifests for bad and good builds mkdir -p bad/artifacts good/artifacts curl -o bad/artifacts/manifest.sh https://ci.linaro.org/job/tcwg_kernel-gnu-build-gnu-release-aarch64-next-all... --fail curl -o good/artifacts/manifest.sh https://ci.linaro.org/job/tcwg_kernel-gnu-build-gnu-release-aarch64-next-all... --fail

# Reproduce bad build (cd bad; ../jenkins-scripts/tcwg_kernel-build.sh ^^ true %%rr[top_artifacts] artifacts) # Reproduce good build (cd good; ../jenkins-scripts/tcwg_kernel-build.sh ^^ true %%rr[top_artifacts] artifacts) </cut>

Full commit (up to 1000 lines): <cut> commit 9ed2b4616d4e846ece2a04cb5007ce1d1bd9e3f3 Author: Anshuman Khandual anshuman.khandual@arm.com Date: Fri Nov 18 11:01:02 2022 +0530

arm64/mm: Drop redundant BUG_ON(!pgtable_alloc)

__create_pgd_mapping_locked() expects a page allocator used while mapping a virtual range. This page allocator function propagates down the call chain, while building intermediate levels in the page table. Passed page allocator is a necessary ingredient required to build the page table but its presence can be asserted just once in the very beginning rather than in all the down stream functions. This consolidates BUG_ON(!pgtable_alloc) checks just in a single place i.e __create_pgd_mapping_locked().

Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Andrew Morton akpm@linux-foundation.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual anshuman.khandual@arm.com Acked-by: Mark Rutland mark.rutland@arm.com Link: https://lore.kernel.org/r/20221118053102.500216-1-anshuman.khandual@arm.com Signed-off-by: Will Deacon will@kernel.org --- arch/arm64/mm/mmu.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index d386033a074c..73a12b3abf82 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -207,7 +207,6 @@ static void alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr,

if (flags & NO_EXEC_MAPPINGS) pmdval |= PMD_TABLE_PXN; - BUG_ON(!pgtable_alloc); pte_phys = pgtable_alloc(PAGE_SHIFT); __pmd_populate(pmdp, pte_phys, pmdval); pmd = READ_ONCE(*pmdp); @@ -285,7 +284,6 @@ static void alloc_init_cont_pmd(pud_t *pudp, unsigned long addr,

if (flags & NO_EXEC_MAPPINGS) pudval |= PUD_TABLE_PXN; - BUG_ON(!pgtable_alloc); pmd_phys = pgtable_alloc(PMD_SHIFT); __pud_populate(pudp, pmd_phys, pudval); pud = READ_ONCE(*pudp); @@ -324,7 +322,6 @@ static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end,

if (flags & NO_EXEC_MAPPINGS) p4dval |= P4D_TABLE_PXN; - BUG_ON(!pgtable_alloc); pud_phys = pgtable_alloc(PUD_SHIFT); __p4d_populate(p4dp, pud_phys, p4dval); p4d = READ_ONCE(*p4dp); @@ -383,6 +380,7 @@ static void __create_pgd_mapping_locked(pgd_t *pgdir, phys_addr_t phys, phys &= PAGE_MASK; addr = virt & PAGE_MASK; end = PAGE_ALIGN(virt + size); + BUG_ON(!pgtable_alloc);

do { next = pgd_addr_end(addr, end); </cut>