Re: [PATCH V9] mm/debug: Add tests validating architecture page table helpers
On 11/12/2019 11:59 AM, Ingo Molnar wrote: > > * Anshuman Khandual wrote: > >> +config DEBUG_VM_PGTABLE >> +bool "Debug arch page table for semantics compliance" >> +depends on MMU >> +depends on DEBUG_VM >> +depends on ARCH_HAS_DEBUG_VM_PGTABLE >> +help >> + This option provides a debug method which can be used to test >> + architecture page table helper functions on various platforms in >> + verifying if they comply with expected generic MM semantics. This >> + will help architecture code in making sure that any changes or >> + new additions of these helpers still conform to expected >> + semantics of the generic MM. >> + >> + If unsure, say N. > > Since CONFIG_DEBUG_VM is generally disabled in distro kernel packages, > why not make this 'default y' to maximize testing coverage? The code size > increase should be minimal, and DEBUG_VM increases size anyway. Sure, will do. > > Other than that this looks good to me: > > Reviewed-by: Ingo Molnar Thank you. > > Thanks, > > Ingo >
Re: [PATCH V9] mm/debug: Add tests validating architecture page table helpers
* Anshuman Khandual wrote: > +config DEBUG_VM_PGTABLE > + bool "Debug arch page table for semantics compliance" > + depends on MMU > + depends on DEBUG_VM > + depends on ARCH_HAS_DEBUG_VM_PGTABLE > + help > + This option provides a debug method which can be used to test > + architecture page table helper functions on various platforms in > + verifying if they comply with expected generic MM semantics. This > + will help architecture code in making sure that any changes or > + new additions of these helpers still conform to expected > + semantics of the generic MM. > + > + If unsure, say N. Since CONFIG_DEBUG_VM is generally disabled in distro kernel packages, why not make this 'default y' to maximize testing coverage? The code size increase should be minimal, and DEBUG_VM increases size anyway. Other than that this looks good to me: Reviewed-by: Ingo Molnar Thanks, Ingo
Re: [PATCH V9] mm/debug: Add tests validating architecture page table helpers
On 11/12/2019 09:48 AM, Anshuman Khandual wrote: > This adds tests which will validate architecture page table helpers and > other accessors in their compliance with expected generic MM semantics. > This will help various architectures in validating changes to existing > page table helpers or addition of new ones. > > This test covers basic page table entry transformations including but not > limited to old, young, dirty, clean, write, write protect etc at various > level along with populating intermediate entries with next page table page > and validating them. > > Test page table pages are allocated from system memory with required size > and alignments. The mapped pfns at page table levels are derived from a > real pfn representing a valid kernel text symbol. This test gets called > right after page_alloc_init_late(). > > This gets build and run when CONFIG_DEBUG_VM_PGTABLE is selected along with > CONFIG_VM_DEBUG. Architectures willing to subscribe this test also need to > select CONFIG_ARCH_HAS_DEBUG_VM_PGTABLE which for now is limited to x86 and > arm64. Going forward, other architectures too can enable this after fixing > build or runtime problems (if any) with their page table helpers. > > Folks interested in making sure that a given platform's page table helpers > conform to expected generic MM semantics should enable the above config > which will just trigger this test during boot. Any non conformity here will > be reported as an warning which would need to be fixed. This test will help > catch any changes to the agreed upon semantics expected from generic MM and > enable platforms to accommodate it thereafter. > > Cc: Andrew Morton > Cc: Vlastimil Babka > Cc: Greg Kroah-Hartman > Cc: Thomas Gleixner > Cc: Mike Rapoport > Cc: Jason Gunthorpe > Cc: Dan Williams > Cc: Peter Zijlstra > Cc: Michal Hocko > Cc: Mark Rutland > Cc: Mark Brown > Cc: Steven Price > Cc: Ard Biesheuvel > Cc: Masahiro Yamada > Cc: Kees Cook > Cc: Tetsuo Handa > Cc: Matthew Wilcox > Cc: Sri Krishna chowdary > Cc: Dave Hansen > Cc: Russell King - ARM Linux > Cc: Michael Ellerman > Cc: Paul Mackerras > Cc: Martin Schwidefsky > Cc: Heiko Carstens > Cc: "David S. Miller" > Cc: Vineet Gupta > Cc: James Hogan > Cc: Paul Burton > Cc: Ralf Baechle > Cc: Kirill A. Shutemov > Cc: Gerald Schaefer > Cc: Christophe Leroy > Cc: Ingo Molnar > Cc: linux-snps-...@lists.infradead.org > Cc: linux-m...@vger.kernel.org > Cc: linux-arm-ker...@lists.infradead.org > Cc: linux-i...@vger.kernel.org > Cc: linuxppc-dev@lists.ozlabs.org > Cc: linux-s...@vger.kernel.org > Cc: linux...@vger.kernel.org > Cc: sparcli...@vger.kernel.org > Cc: x...@kernel.org > Cc: linux-ker...@vger.kernel.org > > Tested-by: Christophe Leroy #PPC32 > Suggested-by: Catalin Marinas > Signed-off-by: Andrew Morton > Signed-off-by: Christophe Leroy > Signed-off-by: Anshuman Khandual > --- > This adds a test validation for architecture exported page table helpers. > Patch adds basic transformation tests at various levels of the page table. > > This test was originally suggested by Catalin during arm64 THP migration > RFC discussion earlier. Going forward it can include more specific tests > with respect to various generic MM functions like THP, HugeTLB etc and > platform specific tests. > > https://lore.kernel.org/linux-mm/20190628102003.ga56...@arrakis.emea.arm.com/ > > Needs to be applied on linux-next (next-20191025). > > Changes in V9: > > - Changed feature support enumeration for powerpc platforms per Christophe > - Changed config wrapper for basic_[pmd|pud]_tests() to enable ARC platform > - Enabled the test on ARC platform But this does not actually subscribe ARCH_HAS_DEBUG_VM_PGTABLE on ARC platform. Please ignore this one, will resend.
[PATCH V9] mm/debug: Add tests validating architecture page table helpers
This adds tests which will validate architecture page table helpers and other accessors in their compliance with expected generic MM semantics. This will help various architectures in validating changes to existing page table helpers or addition of new ones. This test covers basic page table entry transformations including but not limited to old, young, dirty, clean, write, write protect etc at various level along with populating intermediate entries with next page table page and validating them. Test page table pages are allocated from system memory with required size and alignments. The mapped pfns at page table levels are derived from a real pfn representing a valid kernel text symbol. This test gets called right after page_alloc_init_late(). This gets build and run when CONFIG_DEBUG_VM_PGTABLE is selected along with CONFIG_VM_DEBUG. Architectures willing to subscribe this test also need to select CONFIG_ARCH_HAS_DEBUG_VM_PGTABLE which for now is limited to x86 and arm64. Going forward, other architectures too can enable this after fixing build or runtime problems (if any) with their page table helpers. Folks interested in making sure that a given platform's page table helpers conform to expected generic MM semantics should enable the above config which will just trigger this test during boot. Any non conformity here will be reported as an warning which would need to be fixed. This test will help catch any changes to the agreed upon semantics expected from generic MM and enable platforms to accommodate it thereafter. Cc: Andrew Morton Cc: Vlastimil Babka Cc: Greg Kroah-Hartman Cc: Thomas Gleixner Cc: Mike Rapoport Cc: Jason Gunthorpe Cc: Dan Williams Cc: Peter Zijlstra Cc: Michal Hocko Cc: Mark Rutland Cc: Mark Brown Cc: Steven Price Cc: Ard Biesheuvel Cc: Masahiro Yamada Cc: Kees Cook Cc: Tetsuo Handa Cc: Matthew Wilcox Cc: Sri Krishna chowdary Cc: Dave Hansen Cc: Russell King - ARM Linux Cc: Michael Ellerman Cc: Paul Mackerras Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: "David S. Miller" Cc: Vineet Gupta Cc: James Hogan Cc: Paul Burton Cc: Ralf Baechle Cc: Kirill A. Shutemov Cc: Gerald Schaefer Cc: Christophe Leroy Cc: Ingo Molnar Cc: linux-snps-...@lists.infradead.org Cc: linux-m...@vger.kernel.org Cc: linux-arm-ker...@lists.infradead.org Cc: linux-i...@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-s...@vger.kernel.org Cc: linux...@vger.kernel.org Cc: sparcli...@vger.kernel.org Cc: x...@kernel.org Cc: linux-ker...@vger.kernel.org Tested-by: Christophe Leroy#PPC32 Suggested-by: Catalin Marinas Signed-off-by: Andrew Morton Signed-off-by: Christophe Leroy Signed-off-by: Anshuman Khandual --- This adds a test validation for architecture exported page table helpers. Patch adds basic transformation tests at various levels of the page table. This test was originally suggested by Catalin during arm64 THP migration RFC discussion earlier. Going forward it can include more specific tests with respect to various generic MM functions like THP, HugeTLB etc and platform specific tests. https://lore.kernel.org/linux-mm/20190628102003.ga56...@arrakis.emea.arm.com/ Needs to be applied on linux-next (next-20191025). Changes in V9: - Changed feature support enumeration for powerpc platforms per Christophe - Changed config wrapper for basic_[pmd|pud]_tests() to enable ARC platform - Enabled the test on ARC platform Changes in V8: (https://patchwork.kernel.org/project/linux-mm/list/?series=194297) - Enabled ARCH_HAS_DEBUG_VM_PGTABLE on PPC32 platform per Christophe - Updated feature documentation as DEBUG_VM_PGTABLE is now enabled on PPC32 platform - Moved ARCH_HAS_DEBUG_VM_PGTABLE earlier to indent it with DEBUG_VM per Christophe - Added an information message in debug_vm_pgtable() per Christophe - Dropped random_vaddr boundary condition checks per Christophe and Qian - Replaced virt_addr_valid() check with pfn_valid() check in debug_vm_pgtable() - Slightly changed pr_fmt(fmt) information Changes in V7: (https://patchwork.kernel.org/project/linux-mm/list/?series=193051) - Memory allocation and free routines for mapped pages have been droped - Mapped pfns are derived from standard kernel text symbol per Matthew - Moved debug_vm_pgtaable() after page_alloc_init_late() per Michal and Qian - Updated the commit message per Michal - Updated W=1 GCC warning problem on x86 per Qian Cai - Addition of new alloc_contig_pages() helper has been submitted separately Changes in V6: (https://patchwork.kernel.org/project/linux-mm/list/?series=187589) - Moved alloc_gigantic_page_order() into mm/page_alloc.c per Michal - Moved alloc_gigantic_page_order() within CONFIG_CONTIG_ALLOC in the test - Folded Andrew's include/asm-generic/pgtable.h fix into the test patch 2/2 Changes in V5: (https://patchwork.kernel.org/project/linux-mm/list/?series=185991) - Redefined and moved X86 mm_p4d_folded() into a different header per Kirill/Ingo - Updated the
