[PATCH] mm: use enum for vm_flags

[Jakub Acs <acsjakub@amazon.de>]

redefine VM_* flag constants with BIT()

Make VM_* flag constant definitions consistent - unify all to use BIT()
macro and define them within an enum.

The bindgen tool is better able to handle BIT(_) declarations when used
in an enum.

Also add enum definitions for tracepoints.

We have previously changed VM_MERGEABLE in a separate bugfix. This is a
follow-up to make all the VM_* flag constant definitions consistent, as
suggested by David in [1].

[1]: https://lore.kernel.org/all/85f852f9-8577-4230-adc7-c52e7f479454@redhat.com/

Signed-off-by: Jakub Acs <acsjakub@amazon.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Xu Xin <xu.xin16@zte.com.cn>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---

Hi Alice,

thanks for the patch, I squashed it in (should I add your signed-off-by
too?) and added the TRACE_DEFINE_ENUM calls pointed out by Derrick.

I have the following points to still address, though: 

- can the fact that we're not controlling the type of the values if
  using enum be a problem? (likely the indirect control we have through
  the highest value is good enough, but I'm not sure)

- where do TRACE_DEFINE_ENUM calls belong?
  I see them placed e.g. in include/trace/misc/nfs.h for nfs or
  arch/x86/kvm/mmu/mmutrace.h, but I don't see a corresponding file for
  mm.h - does this warrant creating a separate file for these
  definitions?

- with the need for TRACE_DEFINE_ENUM calls, do we still deem this
  to be a good trade-off? - isn't fixing all of these in
  rust/bindings/bindings_helper.h better?

@Derrick, can you point me to how to test for the issue you pointed out?

Thanks,
Jakub


 include/linux/mm.h              | 142 ++++++++++++++++++++++----------
 rust/bindings/bindings_helper.h |   1 -
 2 files changed, 98 insertions(+), 45 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 70a2a76007d4..8b9e7a9e7042 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -36,6 +36,7 @@
 #include <linux/rcuwait.h>
 #include <linux/bitmap.h>
 #include <linux/bitops.h>
+#include <linux/tracepoint.h>
 
 struct mempolicy;
 struct anon_vma;
@@ -273,57 +274,58 @@ extern unsigned int kobjsize(const void *objp);
  * vm_flags in vm_area_struct, see mm_types.h.
  * When changing, update also include/trace/events/mmflags.h
  */
-#define VM_NONE		0x00000000
+enum {
+	VM_NONE		= 0,
 
-#define VM_READ		0x00000001	/* currently active flags */
-#define VM_WRITE	0x00000002
-#define VM_EXEC		0x00000004
-#define VM_SHARED	0x00000008
+	VM_READ		= BIT(0),		/* currently active flags */
+	VM_WRITE	= BIT(1),
+	VM_EXEC		= BIT(2),
+	VM_SHARED	= BIT(3),
 
 /* mprotect() hardcodes VM_MAYREAD >> 4 == VM_READ, and so for r/w/x bits. */
-#define VM_MAYREAD	0x00000010	/* limits for mprotect() etc */
-#define VM_MAYWRITE	0x00000020
-#define VM_MAYEXEC	0x00000040
-#define VM_MAYSHARE	0x00000080
+	VM_MAYREAD	= BIT(4),		/* limits for mprotect() etc */
+	VM_MAYWRITE	= BIT(5),
+	VM_MAYEXEC	= BIT(6),
+	VM_MAYSHARE	= BIT(7),
 
-#define VM_GROWSDOWN	0x00000100	/* general info on the segment */
+	VM_GROWSDOWN	= BIT(8),		/* general info on the segment */
 #ifdef CONFIG_MMU
-#define VM_UFFD_MISSING	0x00000200	/* missing pages tracking */
+	VM_UFFD_MISSING	= BIT(9),		/* missing pages tracking */
 #else /* CONFIG_MMU */
-#define VM_MAYOVERLAY	0x00000200	/* nommu: R/O MAP_PRIVATE mapping that might overlay a file mapping */
+	VM_MAYOVERLAY	= BIT(9),		/* nommu: R/O MAP_PRIVATE mapping that might overlay a file mapping */
 #define VM_UFFD_MISSING	0
 #endif /* CONFIG_MMU */
-#define VM_PFNMAP	0x00000400	/* Page-ranges managed without "struct page", just pure PFN */
-#define VM_UFFD_WP	0x00001000	/* wrprotect pages tracking */
-
-#define VM_LOCKED	0x00002000
-#define VM_IO           0x00004000	/* Memory mapped I/O or similar */
-
-					/* Used by sys_madvise() */
-#define VM_SEQ_READ	0x00008000	/* App will access data sequentially */
-#define VM_RAND_READ	0x00010000	/* App will not benefit from clustered reads */
-
-#define VM_DONTCOPY	0x00020000      /* Do not copy this vma on fork */
-#define VM_DONTEXPAND	0x00040000	/* Cannot expand with mremap() */
-#define VM_LOCKONFAULT	0x00080000	/* Lock the pages covered when they are faulted in */
-#define VM_ACCOUNT	0x00100000	/* Is a VM accounted object */
-#define VM_NORESERVE	0x00200000	/* should the VM suppress accounting */
-#define VM_HUGETLB	0x00400000	/* Huge TLB Page VM */
-#define VM_SYNC		0x00800000	/* Synchronous page faults */
-#define VM_ARCH_1	0x01000000	/* Architecture-specific flag */
-#define VM_WIPEONFORK	0x02000000	/* Wipe VMA contents in child. */
-#define VM_DONTDUMP	0x04000000	/* Do not include in the core dump */
+	VM_PFNMAP	= BIT(10),		/* Page-ranges managed without "struct page", just pure PFN */
+	VM_UFFD_WP	= BIT(12),		/* wrprotect pages tracking */
+
+	VM_LOCKED	= BIT(13),
+	VM_IO           = BIT(14),		/* Memory mapped I/O or similar */
+
+						/* Used by sys_madvise() */
+	VM_SEQ_READ	= BIT(15),		/* App will access data sequentially */
+	VM_RAND_READ	= BIT(16),		/* App will not benefit from clustered reads */
+
+	VM_DONTCOPY	= BIT(17),		/* Do not copy this vma on fork */
+	VM_DONTEXPAND	= BIT(18),		/* Cannot expand with mremap() */
+	VM_LOCKONFAULT	= BIT(19),		/* Lock the pages covered when they are faulted in */
+	VM_ACCOUNT	= BIT(20),		/* Is a VM accounted object */
+	VM_NORESERVE	= BIT(21),		/* should the VM suppress accounting */
+	VM_HUGETLB	= BIT(22),		/* Huge TLB Page VM */
+	VM_SYNC		= BIT(23),		/* Synchronous page faults */
+	VM_ARCH_1	= BIT(24),		/* Architecture-specific flag */
+	VM_WIPEONFORK	= BIT(25),		/* Wipe VMA contents in child. */
+	VM_DONTDUMP	= BIT(26),		/* Do not include in the core dump */
 
 #ifdef CONFIG_MEM_SOFT_DIRTY
-# define VM_SOFTDIRTY	0x08000000	/* Not soft dirty clean area */
+	VM_SOFTDIRTY	= BIT(27),		/* Not soft dirty clean area */
 #else
 # define VM_SOFTDIRTY	0
 #endif
 
-#define VM_MIXEDMAP	0x10000000	/* Can contain "struct page" and pure PFN pages */
-#define VM_HUGEPAGE	0x20000000	/* MADV_HUGEPAGE marked this vma */
-#define VM_NOHUGEPAGE	0x40000000	/* MADV_NOHUGEPAGE marked this vma */
-#define VM_MERGEABLE	BIT(31)		/* KSM may merge identical pages */
+	VM_MIXEDMAP	= BIT(28),		/* Can contain "struct page" and pure PFN pages */
+	VM_HUGEPAGE	= BIT(29),		/* MADV_HUGEPAGE marked this vma */
+	VM_NOHUGEPAGE	= BIT(30),		/* MADV_NOHUGEPAGE marked this vma */
+	VM_MERGEABLE	= BIT(31),		/* KSM may merge identical pages */
 
 #ifdef CONFIG_ARCH_USES_HIGH_VMA_FLAGS
 #define VM_HIGH_ARCH_BIT_0	32	/* bit only usable on 64-bit architectures */
@@ -333,14 +335,66 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_HIGH_ARCH_BIT_4	36	/* bit only usable on 64-bit architectures */
 #define VM_HIGH_ARCH_BIT_5	37	/* bit only usable on 64-bit architectures */
 #define VM_HIGH_ARCH_BIT_6	38	/* bit only usable on 64-bit architectures */
-#define VM_HIGH_ARCH_0	BIT(VM_HIGH_ARCH_BIT_0)
-#define VM_HIGH_ARCH_1	BIT(VM_HIGH_ARCH_BIT_1)
-#define VM_HIGH_ARCH_2	BIT(VM_HIGH_ARCH_BIT_2)
-#define VM_HIGH_ARCH_3	BIT(VM_HIGH_ARCH_BIT_3)
-#define VM_HIGH_ARCH_4	BIT(VM_HIGH_ARCH_BIT_4)
-#define VM_HIGH_ARCH_5	BIT(VM_HIGH_ARCH_BIT_5)
-#define VM_HIGH_ARCH_6	BIT(VM_HIGH_ARCH_BIT_6)
+	VM_HIGH_ARCH_0	= BIT(VM_HIGH_ARCH_BIT_0),
+	VM_HIGH_ARCH_1	= BIT(VM_HIGH_ARCH_BIT_1),
+	VM_HIGH_ARCH_2	= BIT(VM_HIGH_ARCH_BIT_2),
+	VM_HIGH_ARCH_3	= BIT(VM_HIGH_ARCH_BIT_3),
+	VM_HIGH_ARCH_4	= BIT(VM_HIGH_ARCH_BIT_4),
+	VM_HIGH_ARCH_5	= BIT(VM_HIGH_ARCH_BIT_5),
+	VM_HIGH_ARCH_6	= BIT(VM_HIGH_ARCH_BIT_6),
 #endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */
+};
+
+TRACE_DEFINE_ENUM(VM_NONE);
+TRACE_DEFINE_ENUM(VM_READ);
+TRACE_DEFINE_ENUM(VM_WRITE);
+TRACE_DEFINE_ENUM(VM_EXEC);
+TRACE_DEFINE_ENUM(VM_SHARED);
+TRACE_DEFINE_ENUM(VM_MAYREAD);
+TRACE_DEFINE_ENUM(VM_MAYWRITE);
+TRACE_DEFINE_ENUM(VM_MAYEXEC);
+TRACE_DEFINE_ENUM(VM_MAYSHARE);
+TRACE_DEFINE_ENUM(VM_GROWSDOWN);
+TRACE_DEFINE_ENUM(VM_UFFD_MISSING);
+
+#ifndef CONFIG_MMU
+TRACE_DEFINE_ENUM(VM_MAYOVERLAY);
+#endif /* CONFIG_MMU */
+
+TRACE_DEFINE_ENUM(VM_PFNMAP);
+TRACE_DEFINE_ENUM(VM_UFFD_WP);
+TRACE_DEFINE_ENUM(VM_LOCKED);
+TRACE_DEFINE_ENUM(VM_IO);
+TRACE_DEFINE_ENUM(VM_SEQ_READ);
+TRACE_DEFINE_ENUM(VM_RAND_READ);
+TRACE_DEFINE_ENUM(VM_DONTCOPY);
+TRACE_DEFINE_ENUM(VM_DONTEXPAND);
+TRACE_DEFINE_ENUM(VM_LOCKONFAULT);
+TRACE_DEFINE_ENUM(VM_ACCOUNT);
+TRACE_DEFINE_ENUM(VM_NORESERVE);
+TRACE_DEFINE_ENUM(VM_HUGETLB);
+TRACE_DEFINE_ENUM(VM_SYNC);
+TRACE_DEFINE_ENUM(VM_ARCH_1);
+TRACE_DEFINE_ENUM(VM_WIPEONFORK);
+TRACE_DEFINE_ENUM(VM_DONTDUMP);
+
+TRACE_DEFINE_ENUM(VM_SOFTDIRTY);
+
+TRACE_DEFINE_ENUM(VM_MIXEDMAP);
+TRACE_DEFINE_ENUM(VM_HUGEPAGE);
+TRACE_DEFINE_ENUM(VM_NOHUGEPAGE);
+TRACE_DEFINE_ENUM(VM_MERGEABLE);
+
+#ifdef CONFIG_ARCH_USES_HIGH_VMA_FLAGS
+TRACE_DEFINE_ENUM(VM_HIGH_ARCH_0);
+TRACE_DEFINE_ENUM(VM_HIGH_ARCH_1);
+TRACE_DEFINE_ENUM(VM_HIGH_ARCH_2);
+TRACE_DEFINE_ENUM(VM_HIGH_ARCH_3);
+TRACE_DEFINE_ENUM(VM_HIGH_ARCH_4);
+TRACE_DEFINE_ENUM(VM_HIGH_ARCH_5);
+TRACE_DEFINE_ENUM(VM_HIGH_ARCH_6);
+#endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */
+
 
 #ifdef CONFIG_ARCH_HAS_PKEYS
 # define VM_PKEY_SHIFT VM_HIGH_ARCH_BIT_0
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 2e43c66635a2..04b75d4d01c3 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -108,7 +108,6 @@ const xa_mark_t RUST_CONST_HELPER_XA_PRESENT = XA_PRESENT;
 
 const gfp_t RUST_CONST_HELPER_XA_FLAGS_ALLOC = XA_FLAGS_ALLOC;
 const gfp_t RUST_CONST_HELPER_XA_FLAGS_ALLOC1 = XA_FLAGS_ALLOC1;
-const vm_flags_t RUST_CONST_HELPER_VM_MERGEABLE = VM_MERGEABLE;
 
 #if IS_ENABLED(CONFIG_ANDROID_BINDER_IPC_RUST)
 #include "../../drivers/android/binder/rust_binder.h"
-- 
2.47.3




Amazon Web Services Development Center Germany GmbH
Tamara-Danz-Str. 13
10243 Berlin
Geschaeftsfuehrung: Christian Schlaeger
Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B
Sitz: Berlin
Ust-ID: DE 365 538 597