| Message ID | 20200428194449.22615-1-willy@infradead.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Record the mm_struct in the page table pages | expand |
On Tue, Apr 28, 2020 at 12:44:42PM -0700, Matthew Wilcox wrote: > From: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > Pages which are in use as page tables have some space unused in struct > page. It would be handy to have a pointer to the struct mm_struct that > they belong to so that we can handle uncorrectable errors in page tables > more gracefully. There are a few other things we could use it for too, > such as checking that the page table entry actually belongs to the task > we think it ought to. This patch series does none of that, but does > lay the groundwork for it. > > Matthew Wilcox (Oracle) (7): How does it work for kernel side of virtual address space? And your employer may be interested in semantics around CONFIG_ARCH_WANT_HUGE_PMD_SHARE :P
On Wed, Apr 29, 2020 at 03:26:24AM +0300, Kirill A. Shutemov wrote: > On Tue, Apr 28, 2020 at 12:44:42PM -0700, Matthew Wilcox wrote: > > From: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > > > Pages which are in use as page tables have some space unused in struct > > page. It would be handy to have a pointer to the struct mm_struct that > > they belong to so that we can handle uncorrectable errors in page tables > > more gracefully. There are a few other things we could use it for too, > > such as checking that the page table entry actually belongs to the task > > we think it ought to. This patch series does none of that, but does > > lay the groundwork for it. > > > > Matthew Wilcox (Oracle) (7): > > How does it work for kernel side of virtual address space? init_mm > And your employer may be interested in semantics around > CONFIG_ARCH_WANT_HUGE_PMD_SHARE :P I was thinking about that. Right now, it's only useful for debugging purposes (as you point out in a later email). I think it's OK if shared PMDs aren't supported as well as regular PTEs, just because there are so few of them that uncorrectable errors are less likely to strike in those pages.
On Tue, Apr 28, 2020 at 06:51:26PM -0700, Matthew Wilcox wrote: > On Wed, Apr 29, 2020 at 03:26:24AM +0300, Kirill A. Shutemov wrote: > > On Tue, Apr 28, 2020 at 12:44:42PM -0700, Matthew Wilcox wrote: > > > From: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > > > > > Pages which are in use as page tables have some space unused in struct > > > page. It would be handy to have a pointer to the struct mm_struct that > > > they belong to so that we can handle uncorrectable errors in page tables > > > more gracefully. There are a few other things we could use it for too, > > > such as checking that the page table entry actually belongs to the task > > > we think it ought to. This patch series does none of that, but does > > > lay the groundwork for it. > > > > > > Matthew Wilcox (Oracle) (7): > > > > How does it work for kernel side of virtual address space? > > init_mm A note to keep in mind is that most of the kernel page tables are seen as PG_reserved rather than PageTable(). > > And your employer may be interested in semantics around > > CONFIG_ARCH_WANT_HUGE_PMD_SHARE :P > > I was thinking about that. Right now, it's only useful for debugging > purposes (as you point out in a later email). I think it's OK if shared > PMDs aren't supported as well as regular PTEs, just because there are > so few of them that uncorrectable errors are less likely to strike in > those pages. >
From: "Matthew Wilcox (Oracle)" <willy@infradead.org> Pages which are in use as page tables have some space unused in struct page. It would be handy to have a pointer to the struct mm_struct that they belong to so that we can handle uncorrectable errors in page tables more gracefully. There are a few other things we could use it for too, such as checking that the page table entry actually belongs to the task we think it ought to. This patch series does none of that, but does lay the groundwork for it. Matthew Wilcox (Oracle) (7): mm: Document x86 uses a linked list of pgds mm: Move pt_mm within struct page arm: Thread mm_struct throughout page table allocation arm64: Thread mm_struct throughout page table allocation m68k: Thread mm_struct throughout page table allocation mm: Set pt_mm in PTE constructor mm: Set pt_mm in PMD constructor arch/arc/include/asm/pgalloc.h | 2 +- arch/arm/mm/mmu.c | 66 ++++++++--------- arch/arm64/include/asm/pgalloc.h | 2 +- arch/arm64/mm/mmu.c | 93 ++++++++++++------------ arch/m68k/include/asm/mcf_pgalloc.h | 2 +- arch/m68k/include/asm/motorola_pgalloc.h | 10 +-- arch/m68k/mm/motorola.c | 4 +- arch/openrisc/include/asm/pgalloc.h | 2 +- arch/powerpc/mm/book3s64/pgtable.c | 2 +- arch/powerpc/mm/pgtable-frag.c | 2 +- arch/s390/include/asm/pgalloc.h | 2 +- arch/s390/mm/pgalloc.c | 2 +- arch/sparc/mm/init_64.c | 2 +- arch/sparc/mm/srmmu.c | 2 +- arch/x86/include/asm/pgalloc.h | 2 +- arch/x86/mm/pgtable.c | 3 +- arch/xtensa/include/asm/pgalloc.h | 2 +- include/asm-generic/pgalloc.h | 2 +- include/linux/mm.h | 18 ++++- include/linux/mm_types.h | 12 +-- 20 files changed, 122 insertions(+), 110 deletions(-) base-commit: 6a8b55ed4056ea5559ebe4f6a4b247f627870d4c