On 9/3/24 4:40 PM, James Houghton wrote:
On Tue, Sep 3, 2024 at 4:23 PM Anthony Yznaga <anthony.yznaga@xxxxxxxxxx> wrote:From: Khalid Aziz <khalid@xxxxxxxxxx> Add a bit to vm_flags to indicate a vma shares PTEs with others. Add a function to determine if a vma shares PTEs by checking this flag. This is to be used to find the shared page table entries on page fault for vmas sharing PTEs. Signed-off-by: Khalid Aziz <khalid@xxxxxxxxxx> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Signed-off-by: Anthony Yznaga <anthony.yznaga@xxxxxxxxxx> --- include/linux/mm.h | 7 +++++++ include/trace/events/mmflags.h | 3 +++ mm/internal.h | 5 +++++ 3 files changed, 15 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index 6549d0979b28..3aa0b3322284 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -413,6 +413,13 @@ extern unsigned int kobjsize(const void *objp); #define VM_DROPPABLE VM_NONE #endif +#ifdef CONFIG_64BIT +#define VM_SHARED_PT_BIT 41 +#define VM_SHARED_PT BIT(VM_SHARED_PT_BIT) +#else +#define VM_SHARED_PT VM_NONE +#endif + #ifdef CONFIG_64BIT /* VM is sealed, in vm_flags */ #define VM_SEALED _BITUL(63) diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h index b63d211bd141..e1ae1e60d086 100644 --- a/include/trace/events/mmflags.h +++ b/include/trace/events/mmflags.h @@ -167,8 +167,10 @@ IF_HAVE_PG_ARCH_X(arch_3) #ifdef CONFIG_64BIT # define IF_HAVE_VM_DROPPABLE(flag, name) {flag, name}, +# define IF_HAVE_VM_SHARED_PT(flag, name) {flag, name}, #else # define IF_HAVE_VM_DROPPABLE(flag, name) +# define IF_HAVE_VM_SHARED_PT(flag, name) #endif #define __def_vmaflag_names \ @@ -204,6 +206,7 @@ IF_HAVE_VM_SOFTDIRTY(VM_SOFTDIRTY, "softdirty" ) \ {VM_HUGEPAGE, "hugepage" }, \ {VM_NOHUGEPAGE, "nohugepage" }, \ IF_HAVE_VM_DROPPABLE(VM_DROPPABLE, "droppable" ) \ +IF_HAVE_VM_SHARED_PT(VM_SHARED_PT, "sharedpt" ) \ {VM_MERGEABLE, "mergeable" } \ #define show_vma_flags(flags) \ diff --git a/mm/internal.h b/mm/internal.h index b4d86436565b..8005d5956b6e 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1578,4 +1578,9 @@ void unlink_file_vma_batch_init(struct unlink_vma_file_batch *); void unlink_file_vma_batch_add(struct unlink_vma_file_batch *, struct vm_area_struct *); void unlink_file_vma_batch_final(struct unlink_vma_file_batch *);
Hi James,
Hi Anthony, I'm really excited to see this series on the mailing list again! :) I won't have time to review this series in too much detail, but I hope something like it gets merged eventually.
Me, too. :-)
+static inline bool vma_is_shared(const struct vm_area_struct *vma) +{ + return VM_SHARED_PT && (vma->vm_flags & VM_SHARED_PT); +}Tiny comment - I find vma_is_shared() to be a bit of a confusing name, especially given how vma_is_shared_maywrite() is defined. (Sorry if this has already been discussed before.) How about vma_is_shared_pt()?
Good point. I'll make this change. Thanks for taking a look. Anthony
