Messages in this thread | | | Subject | Re: [RFC PATCH 1/7] mm: Add write-protect and clean utilities for address space ranges | From | Thomas Hellström (VMware) <> | Date | Fri, 13 Sep 2019 13:11:59 +0200 |
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On 9/13/19 11:32 AM, Thomas Hellström (VMware) wrote: > From: Thomas Hellstrom <thellstrom@vmware.com> > > Add two utilities to a) write-protect and b) clean all ptes pointing into > a range of an address space. > The utilities are intended to aid in tracking dirty pages (either > driver-allocated system memory or pci device memory). > The write-protect utility should be used in conjunction with > page_mkwrite() and pfn_mkwrite() to trigger write page-faults on page > accesses. Typically one would want to use this on sparse accesses into > large memory regions. The clean utility should be used to utilize > hardware dirtying functionality and avoid the overhead of page-faults, > typically on large accesses into small memory regions. > > The added file "as_dirty_helpers.c" is initially listed as maintained by > VMware under our DRM driver. If somebody would like it elsewhere, > that's of course no problem. > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Rik van Riel <riel@surriel.com> > Cc: Minchan Kim <minchan@kernel.org> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Huang Ying <ying.huang@intel.com> > Cc: Souptick Joarder <jrdr.linux@gmail.com> > Cc: "Jérôme Glisse" <jglisse@redhat.com> > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > > Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> > Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> #v1 > --- > MAINTAINERS | 1 + > include/linux/mm.h | 13 +- > mm/Kconfig | 3 + > mm/Makefile | 1 + > mm/as_dirty_helpers.c | 392 ++++++++++++++++++++++++++++++++++++++++++ > 5 files changed, 409 insertions(+), 1 deletion(-) > create mode 100644 mm/as_dirty_helpers.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index c2d975da561f..b596c7cf4a85 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -5287,6 +5287,7 @@ T: git git://people.freedesktop.org/~thomash/linux > S: Supported > F: drivers/gpu/drm/vmwgfx/ > F: include/uapi/drm/vmwgfx_drm.h > +F: mm/as_dirty_helpers.c > > DRM DRIVERS > M: David Airlie <airlied@linux.ie> > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 0334ca97c584..27ff341ecbdc 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2657,7 +2657,6 @@ typedef int (*pte_fn_t)(pte_t *pte, unsigned long addr, void *data); > extern int apply_to_page_range(struct mm_struct *mm, unsigned long address, > unsigned long size, pte_fn_t fn, void *data); > > - > #ifdef CONFIG_PAGE_POISONING > extern bool page_poisoning_enabled(void); > extern void kernel_poison_pages(struct page *page, int numpages, int enable); > @@ -2891,5 +2890,17 @@ void __init setup_nr_node_ids(void); > static inline void setup_nr_node_ids(void) {} > #endif > > +#ifdef CONFIG_AS_DIRTY_HELPERS > +unsigned long apply_as_clean(struct address_space *mapping, > + pgoff_t first_index, pgoff_t nr, > + pgoff_t bitmap_pgoff, > + unsigned long *bitmap, > + pgoff_t *start, > + pgoff_t *end); > + > +unsigned long apply_as_wrprotect(struct address_space *mapping, > + pgoff_t first_index, pgoff_t nr); > +#endif > + > #endif /* __KERNEL__ */ > #endif /* _LINUX_MM_H */ > diff --git a/mm/Kconfig b/mm/Kconfig > index 56cec636a1fc..594350e9d78e 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -736,4 +736,7 @@ config ARCH_HAS_PTE_SPECIAL > config ARCH_HAS_HUGEPD > bool > > +config AS_DIRTY_HELPERS > + bool > + > endmenu > diff --git a/mm/Makefile b/mm/Makefile > index d0b295c3b764..4086f1eefbc6 100644 > --- a/mm/Makefile > +++ b/mm/Makefile > @@ -105,3 +105,4 @@ obj-$(CONFIG_PERCPU_STATS) += percpu-stats.o > obj-$(CONFIG_ZONE_DEVICE) += memremap.o > obj-$(CONFIG_HMM_MIRROR) += hmm.o > obj-$(CONFIG_MEMFD_CREATE) += memfd.o > +obj-$(CONFIG_AS_DIRTY_HELPERS) += as_dirty_helpers.o > diff --git a/mm/as_dirty_helpers.c b/mm/as_dirty_helpers.c > new file mode 100644 > index 000000000000..3be06fe8f1d2 > --- /dev/null > +++ b/mm/as_dirty_helpers.c > @@ -0,0 +1,392 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#include <linux/mm.h> > +#include <linux/mm_types.h> > +#include <linux/hugetlb.h> > +#include <linux/bitops.h> > +#include <linux/mmu_notifier.h> > +#include <asm/cacheflush.h> > +#include <asm/tlbflush.h> > + > +/** > + * struct as_walk - Argument to as_pte_fn_t
Argument to struct as_walk_ops callbacks
> + * @vma: Pointer to the struct vmw_area_struct currently being walked. > + * > + * Embeddable argument to struct as__pte_fn_t
Here as well.
> + */ > +struct as_walk { > + struct vm_area_struct *vma; > +}; > + > +/** > + * struct as_walk_ops - Callbacks for entries of various page table levels. > + * extend for additional level support. > + */ > +struct as_walk_ops { > + /** > + * pte-entry: Callback for PTEs > + * @pte: Pointer to the PTE. > + * @addr: Virtual address. > + * @asw: Struct as_walk argument for the walk. Embed for additional > + * data. > + */ > + void (*const pte_entry) (pte_t *pte, unsigned long addr, > + struct as_walk *asw); > +};
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