| Message ID | 20200703153718.16973-7-catalin.marinas@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Memory Tagging Extension user-space support | expand |
On 03.07.20 17:36, Catalin Marinas wrote: > From: Steven Price <steven.price@arm.com> > > For arm64 MTE support it is necessary to be able to mark pages that > contain user space visible tags that will need to be saved/restored e.g. > when swapped out. > > To support this add a new arch specific flag (PG_arch_2). This flag is > only available on 64-bit architectures due to the limited number of > spare page flags on the 32-bit ones. > > Signed-off-by: Steven Price <steven.price@arm.com> > [catalin.marinas@arm.com: use CONFIG_64BIT for guarding this new flag] > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > --- > > Notes: > v6: > - Using CONFIG_64BIT instead of a new CONFIG_ARCH_USES_PG_ARCH_2 option. > > New in v4. > > fs/proc/page.c | 3 +++ > include/linux/kernel-page-flags.h | 1 + > include/linux/page-flags.h | 3 +++ > include/trace/events/mmflags.h | 9 ++++++++- > tools/vm/page-types.c | 2 ++ > 5 files changed, 17 insertions(+), 1 deletion(-) > > diff --git a/fs/proc/page.c b/fs/proc/page.c > index f909243d4a66..9f1077d94cde 100644 > --- a/fs/proc/page.c > +++ b/fs/proc/page.c > @@ -217,6 +217,9 @@ u64 stable_page_flags(struct page *page) > u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2); > u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1); > u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1); > +#ifdef CONFIG_64BIT > + u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2); > +#endif > > return u; > }; > diff --git a/include/linux/kernel-page-flags.h b/include/linux/kernel-page-flags.h > index abd20ef93c98..eee1877a354e 100644 > --- a/include/linux/kernel-page-flags.h > +++ b/include/linux/kernel-page-flags.h > @@ -17,5 +17,6 @@ > #define KPF_ARCH 38 > #define KPF_UNCACHED 39 > #define KPF_SOFTDIRTY 40 > +#define KPF_ARCH_2 41 > > #endif /* LINUX_KERNEL_PAGE_FLAGS_H */ > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index 6be1aa559b1e..276140c94f4a 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -135,6 +135,9 @@ enum pageflags { > #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT) > PG_young, > PG_idle, > +#endif > +#ifdef CONFIG_64BIT > + PG_arch_2, > #endif > __NR_PAGEFLAGS, People are usually *very* picky when it comes to new page flags. It somewhat concerns me that we bump up __NR_PAGEFLAGS for any 64bit arch. That feels wrong.
On Mon, Jul 06, 2020 at 10:24:04AM +0200, David Hildenbrand wrote: > On 03.07.20 17:36, Catalin Marinas wrote: > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > > index 6be1aa559b1e..276140c94f4a 100644 > > --- a/include/linux/page-flags.h > > +++ b/include/linux/page-flags.h > > @@ -135,6 +135,9 @@ enum pageflags { > > #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT) > > PG_young, > > PG_idle, > > +#endif > > +#ifdef CONFIG_64BIT > > + PG_arch_2, > > #endif > > __NR_PAGEFLAGS, > > People are usually *very* picky when it comes to new page flags. It > somewhat concerns me that we bump up __NR_PAGEFLAGS for any 64bit arch. > That feels wrong. It was guarded by a specific config option initially but the comments suggested that it could be dropped for 64-bit architectures: https://lore.kernel.org/linux-arm-kernel/20200624113307.6165b3db2404c9d37b870a90@linux-foundation.org/ The page flags is indeed a pretty limited resource as it also includes the sparsemem section, node and zone fields. However, on 64-bit this should be fine (the sparsemem section is gone with vmemmap support).
On 06.07.20 13:21, Catalin Marinas wrote: > On Mon, Jul 06, 2020 at 10:24:04AM +0200, David Hildenbrand wrote: >> On 03.07.20 17:36, Catalin Marinas wrote: >>> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h >>> index 6be1aa559b1e..276140c94f4a 100644 >>> --- a/include/linux/page-flags.h >>> +++ b/include/linux/page-flags.h >>> @@ -135,6 +135,9 @@ enum pageflags { >>> #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT) >>> PG_young, >>> PG_idle, >>> +#endif >>> +#ifdef CONFIG_64BIT >>> + PG_arch_2, >>> #endif >>> __NR_PAGEFLAGS, >> >> People are usually *very* picky when it comes to new page flags. It >> somewhat concerns me that we bump up __NR_PAGEFLAGS for any 64bit arch. >> That feels wrong. > > It was guarded by a specific config option initially but the comments > suggested that it could be dropped for 64-bit architectures: > > https://lore.kernel.org/linux-arm-kernel/20200624113307.6165b3db2404c9d37b870a90@linux-foundation.org/ > > The page flags is indeed a pretty limited resource as it also includes > the sparsemem section, node and zone fields. However, on 64-bit this > should be fine (the sparsemem section is gone with vmemmap support). Right, so 64bit architectures/configs with SPARSEMEM && !SPARSEMEM_VMEMMAP could be affected only. I think mips would be one example where we don't have VMEMMAP support. For most other 64bit architectures (x86_64, s390x, powerpc, ...) SPARSEMEM_VMEMMAP should be the default (although I've seen bug reports/configs where VMEMMAP was disabled).
diff --git a/fs/proc/page.c b/fs/proc/page.c index f909243d4a66..9f1077d94cde 100644 --- a/fs/proc/page.c +++ b/fs/proc/page.c @@ -217,6 +217,9 @@ u64 stable_page_flags(struct page *page) u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2); u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1); u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1); +#ifdef CONFIG_64BIT + u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2); +#endif return u; }; diff --git a/include/linux/kernel-page-flags.h b/include/linux/kernel-page-flags.h index abd20ef93c98..eee1877a354e 100644 --- a/include/linux/kernel-page-flags.h +++ b/include/linux/kernel-page-flags.h @@ -17,5 +17,6 @@ #define KPF_ARCH 38 #define KPF_UNCACHED 39 #define KPF_SOFTDIRTY 40 +#define KPF_ARCH_2 41 #endif /* LINUX_KERNEL_PAGE_FLAGS_H */ diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 6be1aa559b1e..276140c94f4a 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -135,6 +135,9 @@ enum pageflags { #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT) PG_young, PG_idle, +#endif +#ifdef CONFIG_64BIT + PG_arch_2, #endif __NR_PAGEFLAGS, diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h index 5fb752034386..67018d367b9f 100644 --- a/include/trace/events/mmflags.h +++ b/include/trace/events/mmflags.h @@ -79,6 +79,12 @@ #define IF_HAVE_PG_IDLE(flag,string) #endif +#ifdef CONFIG_64BIT +#define IF_HAVE_PG_ARCH_2(flag,string) ,{1UL << flag, string} +#else +#define IF_HAVE_PG_ARCH_2(flag,string) +#endif + #define __def_pageflag_names \ {1UL << PG_locked, "locked" }, \ {1UL << PG_waiters, "waiters" }, \ @@ -105,7 +111,8 @@ IF_HAVE_PG_MLOCK(PG_mlocked, "mlocked" ) \ IF_HAVE_PG_UNCACHED(PG_uncached, "uncached" ) \ IF_HAVE_PG_HWPOISON(PG_hwpoison, "hwpoison" ) \ IF_HAVE_PG_IDLE(PG_young, "young" ) \ -IF_HAVE_PG_IDLE(PG_idle, "idle" ) +IF_HAVE_PG_IDLE(PG_idle, "idle" ) \ +IF_HAVE_PG_ARCH_2(PG_arch_2, "arch_2" ) #define show_page_flags(flags) \ (flags) ? __print_flags(flags, "|", \ diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c index 58c0eab71bca..0517c744b04e 100644 --- a/tools/vm/page-types.c +++ b/tools/vm/page-types.c @@ -78,6 +78,7 @@ #define KPF_ARCH 38 #define KPF_UNCACHED 39 #define KPF_SOFTDIRTY 40 +#define KPF_ARCH_2 41 /* [48-] take some arbitrary free slots for expanding overloaded flags * not part of kernel API @@ -135,6 +136,7 @@ static const char * const page_flag_names[] = { [KPF_ARCH] = "h:arch", [KPF_UNCACHED] = "c:uncached", [KPF_SOFTDIRTY] = "f:softdirty", + [KPF_ARCH_2] = "H:arch_2", [KPF_READAHEAD] = "I:readahead", [KPF_SLOB_FREE] = "P:slob_free",