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Message-ID: <20251008125427.68735-1-acsjakub@amazon.de>
Date: Wed, 8 Oct 2025 12:54:27 +0000
From: Jakub Acs <acsjakub@...zon.de>
To: <aliceryhl@...gle.com>, <djwong@...nel.org>
CC: <jhubbard@...dia.com>, <acsjakub@...zon.de>, <akpm@...ux-foundation.org>,
<axelrasmussen@...gle.com>, <chengming.zhou@...ux.dev>, <david@...hat.com>,
<linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-mm@...ck.org>, <peterx@...hat.com>, <rust-for-linux@...r.kernel.org>,
<xu.xin16@....com.cn>
Subject: [PATCH] mm: use enum for vm_flags
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@...zon.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: David Hildenbrand <david@...hat.com>
Cc: Xu Xin <xu.xin16@....com.cn>
Cc: Chengming Zhou <chengming.zhou@...ux.dev>
Cc: Peter Xu <peterx@...hat.com>
Cc: Axel Rasmussen <axelrasmussen@...gle.com>
Cc: linux-mm@...ck.org
Cc: linux-kernel@...r.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
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