From: Jason Gunthorpe <jgg@ziepe.ca> To: Steven Price <steven.price@arm.com> Cc: "Mark Rutland" <Mark.Rutland@arm.com>, x86@kernel.org, "Arnd Bergmann" <arnd@arndb.de>, "Ard Biesheuvel" <ard.biesheuvel@linaro.org>, "Peter Zijlstra" <peterz@infradead.org>, "Catalin Marinas" <catalin.marinas@arm.com>, "Dave Hansen" <dave.hansen@linux.intel.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Jérôme Glisse" <jglisse@redhat.com>, "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>, "Andy Lutomirski" <luto@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, "James Morse" <james.morse@arm.com>, "Thomas Gleixner" <tglx@linutronix.de>, "Will Deacon" <will@kernel.org>, "Andrew Morton" <akpm@linux-foundation.org>, linux-arm-kernel@lists.infradead.org, "Liang, Kan" <kan.liang@linux.intel.com> Subject: Re: [PATCH v11 14/22] mm: pagewalk: Add 'depth' parameter to pte_hole Date: Mon, 7 Oct 2019 15:11:13 -0300 [thread overview] Message-ID: <20191007181113.GC13229@ziepe.ca> (raw) In-Reply-To: <6e570d6d-b29f-f4cb-1eb9-6ff6cab15a2e@arm.com> On Mon, Oct 07, 2019 at 05:20:30PM +0100, Steven Price wrote: > On 07/10/2019 17:10, Jason Gunthorpe wrote: > > On Mon, Oct 07, 2019 at 04:38:14PM +0100, Steven Price wrote: > >> diff --git a/mm/hmm.c b/mm/hmm.c > >> index 902f5fa6bf93..34fe904dd417 100644 > >> +++ b/mm/hmm.c > >> @@ -376,7 +376,7 @@ static void hmm_range_need_fault(const struct hmm_vma_walk *hmm_vma_walk, > >> } > >> > >> static int hmm_vma_walk_hole(unsigned long addr, unsigned long end, > >> - struct mm_walk *walk) > >> + __always_unused int depth, struct mm_walk *walk) > > > > It this __always_unused on function arguments something we are doing > > now? > > $ git grep __always_unused | wc -l > 191 > > It's elsewhere in the kernel tree. It seems like a good way of both > documenting and silencing compiler warnings. But I'm open to other > suggestions. The normal kernel build doesn't generate warnings for unused function parameters because there are alot of false positives, IIRC. So, seems weird to see things like this. > > Can we have negative depth? Should it be unsigned? > > As per the documentation added in this patch: > > * @pte_hole: if set, called for each hole at all levels, > * depth is -1 if not known, 0:PGD, 1:P4D, 2:PUD, 3:PMD > * 4:PTE. Any folded depths (where PTRS_PER_P?D is equal > * to 1) are skipped. > > So it's signed to allow "-1" in the cases where pte_hole is called > without knowing the actual depth. This is used in the function > walk_page_test() because it don't walk the actual page tables, but is > called on a VMA instead. This means that there may not be a single depth > for the range provided. So are the depth values below OK? I would have expected -1 by this definition > >> { > >> struct hmm_vma_walk *hmm_vma_walk = walk->private; > >> struct hmm_range *range = hmm_vma_walk->range; > >> @@ -564,7 +564,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, > >> again: > >> pmd = READ_ONCE(*pmdp); > >> if (pmd_none(pmd)) > >> - return hmm_vma_walk_hole(start, end, walk); > >> + return hmm_vma_walk_hole(start, end, 0, walk); > >> > >> if (thp_migration_supported() && is_pmd_migration_entry(pmd)) { > >> bool fault, write_fault; > >> @@ -666,7 +666,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, > >> again: > >> pud = READ_ONCE(*pudp); > >> if (pud_none(pud)) > >> - return hmm_vma_walk_hole(start, end, walk); > >> + return hmm_vma_walk_hole(start, end, 0, walk); > >> > >> if (pud_huge(pud) && pud_devmap(pud)) { > >> unsigned long i, npages, pfn; > >> @@ -674,7 +674,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, > >> bool fault, write_fault; > >> > >> if (!pud_present(pud)) > >> - return hmm_vma_walk_hole(start, end, walk); > >> + return hmm_vma_walk_hole(start, end, 0, walk); > >> > >> i = (addr - range->start) >> PAGE_SHIFT; > >> npages = (end - addr) >> PAGE_SHIFT;
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@ziepe.ca> To: Steven Price <steven.price@arm.com> Cc: "Mark Rutland" <Mark.Rutland@arm.com>, "Dave Hansen" <dave.hansen@linux.intel.com>, "Arnd Bergmann" <arnd@arndb.de>, "Ard Biesheuvel" <ard.biesheuvel@linaro.org>, "Peter Zijlstra" <peterz@infradead.org>, "Catalin Marinas" <catalin.marinas@arm.com>, x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Jérôme Glisse" <jglisse@redhat.com>, "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>, "Andy Lutomirski" <luto@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, "James Morse" <james.morse@arm.com>, "Thomas Gleixner" <tglx@linutronix.de>, "Will Deacon" <will@kernel.org>, "Andrew Morton" <akpm@linux-foundation.org>, linux-arm-kernel@lists.infradead.org, "Liang, Kan" <kan.liang@linux.intel.com> Subject: Re: [PATCH v11 14/22] mm: pagewalk: Add 'depth' parameter to pte_hole Date: Mon, 7 Oct 2019 15:11:13 -0300 [thread overview] Message-ID: <20191007181113.GC13229@ziepe.ca> (raw) In-Reply-To: <6e570d6d-b29f-f4cb-1eb9-6ff6cab15a2e@arm.com> On Mon, Oct 07, 2019 at 05:20:30PM +0100, Steven Price wrote: > On 07/10/2019 17:10, Jason Gunthorpe wrote: > > On Mon, Oct 07, 2019 at 04:38:14PM +0100, Steven Price wrote: > >> diff --git a/mm/hmm.c b/mm/hmm.c > >> index 902f5fa6bf93..34fe904dd417 100644 > >> +++ b/mm/hmm.c > >> @@ -376,7 +376,7 @@ static void hmm_range_need_fault(const struct hmm_vma_walk *hmm_vma_walk, > >> } > >> > >> static int hmm_vma_walk_hole(unsigned long addr, unsigned long end, > >> - struct mm_walk *walk) > >> + __always_unused int depth, struct mm_walk *walk) > > > > It this __always_unused on function arguments something we are doing > > now? > > $ git grep __always_unused | wc -l > 191 > > It's elsewhere in the kernel tree. It seems like a good way of both > documenting and silencing compiler warnings. But I'm open to other > suggestions. The normal kernel build doesn't generate warnings for unused function parameters because there are alot of false positives, IIRC. So, seems weird to see things like this. > > Can we have negative depth? Should it be unsigned? > > As per the documentation added in this patch: > > * @pte_hole: if set, called for each hole at all levels, > * depth is -1 if not known, 0:PGD, 1:P4D, 2:PUD, 3:PMD > * 4:PTE. Any folded depths (where PTRS_PER_P?D is equal > * to 1) are skipped. > > So it's signed to allow "-1" in the cases where pte_hole is called > without knowing the actual depth. This is used in the function > walk_page_test() because it don't walk the actual page tables, but is > called on a VMA instead. This means that there may not be a single depth > for the range provided. So are the depth values below OK? I would have expected -1 by this definition > >> { > >> struct hmm_vma_walk *hmm_vma_walk = walk->private; > >> struct hmm_range *range = hmm_vma_walk->range; > >> @@ -564,7 +564,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, > >> again: > >> pmd = READ_ONCE(*pmdp); > >> if (pmd_none(pmd)) > >> - return hmm_vma_walk_hole(start, end, walk); > >> + return hmm_vma_walk_hole(start, end, 0, walk); > >> > >> if (thp_migration_supported() && is_pmd_migration_entry(pmd)) { > >> bool fault, write_fault; > >> @@ -666,7 +666,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, > >> again: > >> pud = READ_ONCE(*pudp); > >> if (pud_none(pud)) > >> - return hmm_vma_walk_hole(start, end, walk); > >> + return hmm_vma_walk_hole(start, end, 0, walk); > >> > >> if (pud_huge(pud) && pud_devmap(pud)) { > >> unsigned long i, npages, pfn; > >> @@ -674,7 +674,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, > >> bool fault, write_fault; > >> > >> if (!pud_present(pud)) > >> - return hmm_vma_walk_hole(start, end, walk); > >> + return hmm_vma_walk_hole(start, end, 0, walk); > >> > >> i = (addr - range->start) >> PAGE_SHIFT; > >> npages = (end - addr) >> PAGE_SHIFT; _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-10-07 18:11 UTC|newest] Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-10-07 15:38 [PATCH v11 00/22] Generic page walk and ptdump Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 01/22] mm: Add generic p?d_leaf() macros Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 02/22] arc: mm: Add p?d_leaf() definitions Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-08 20:19 ` Vineet Gupta 2019-10-08 20:19 ` Vineet Gupta 2019-10-07 15:38 ` [PATCH v11 03/22] arm: " Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 04/22] arm64: " Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 05/22] mips: " Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 06/22] powerpc: " Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 07/22] riscv: " Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-08 11:31 ` Alex Ghiti 2019-10-08 11:31 ` Alex Ghiti 2019-10-08 11:31 ` Alex Ghiti 2019-10-08 21:33 ` Paul Walmsley 2019-10-08 21:33 ` Paul Walmsley 2019-10-08 21:33 ` Paul Walmsley 2019-10-09 10:55 ` Steven Price 2019-10-09 10:55 ` Steven Price 2019-10-09 10:55 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 08/22] s390: " Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 09/22] sparc: " Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 10/22] x86: " Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 11/22] mm: pagewalk: Add p4d_entry() and pgd_entry() Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 12/22] mm: pagewalk: Allow walking without vma Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 13/22] mm: pagewalk: Add test_p?d callbacks Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 14/22] mm: pagewalk: Add 'depth' parameter to pte_hole Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 16:10 ` Jason Gunthorpe 2019-10-07 16:10 ` Jason Gunthorpe 2019-10-07 16:20 ` Steven Price 2019-10-07 16:20 ` Steven Price 2019-10-07 18:11 ` Jason Gunthorpe [this message] 2019-10-07 18:11 ` Jason Gunthorpe 2019-10-09 11:00 ` Steven Price 2019-10-09 11:00 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 15/22] x86: mm: Point to struct seq_file from struct pg_state Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 16/22] x86: mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 17/22] x86: mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 18/22] x86: mm: Convert ptdump_walk_pgd_level_core() " Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 19/22] mm: Add generic ptdump Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 20/22] x86: mm: Convert dump_pagetables to use walk_page_range Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 21/22] arm64: mm: Convert mm/dump.c to use walk_page_range() Steven Price 2019-10-07 15:38 ` Steven Price 2019-10-07 15:38 ` [PATCH v11 22/22] arm64: mm: Display non-present entries in ptdump Steven Price 2019-10-07 15:38 ` Steven Price
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