From nobody Sat Apr 4 04:48:20 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C6E953F9F56; Fri, 20 Mar 2026 19:39:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774035560; cv=none; b=P+1p2pupdPqiKP7sGNqyoTKwpRvhWYmA3A45QjlM6CvxOwushKK0yRQB7DBlktJ7FJseuYpebizfCkOussCUSxUrQh8LgDgfpHbNmmMerRABEErYfyH0EslwQoFDYgiTVfWO9ShWVOS1/dV1PhGeTTryOuGUBJloiQMuDh6a+qE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774035560; c=relaxed/simple; bh=frZGbChHfZDBR7/pCN2wWxe44RSqCYtYg/5HJ8X7rnk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bqkOE13fliHBiBKKJNkl7nWeFPbUJdveOTROfyx3Za7JVaT2Prk2MGxOZK67eVrMbCkT/aWZULnhrA4m7Z1VlITcyowXxJukRyczt6+vXBejEUVyYll4rw7To/iPCNglYp7QHYcB+1d7+n13+wepIwcVarBM+x7eequwDj4/lNw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bX82bPEa; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bX82bPEa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE33FC4CEF7; Fri, 20 Mar 2026 19:39:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774035560; bh=frZGbChHfZDBR7/pCN2wWxe44RSqCYtYg/5HJ8X7rnk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bX82bPEa9dczbYZwn6vfhbeDK+Ajku+xA9x1MdDEsvLROP2EOfKP+e+ANeFkz5xMy OclEVmr33n+GqODBneGwuAlRCKiBQxo8WWqOYcdaJ0YNQOauhqIvhCCfI93kQ8a46t KIq0Ur5WXfClxDm8st4KHFzoN13nG4Ib+X8KOcASJfZyeyKJ8J09cIFVUNhA5Ky5Kf ixa08AIO4H+20X7qSKi4d7M9BaJbUJjkqKcNoQKgCcQCqDUz9SwTHZoO3X0dOZstu5 8a4GUv7HoIOWTOUPClkpq7+CPWVvfFpqdnmoqDEyyR6CSVjvESquXJk3FWcSTB3Ftg wSjHWNf9uxzBQ== From: "Lorenzo Stoakes (Oracle)" To: Andrew Morton Cc: David Hildenbrand , "Liam R . Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , Mike Rapoport , Suren Baghdasaryan , Kees Cook , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vineet Gupta , Russell King , Catalin Marinas , Will Deacon , Brian Cain , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , Dinh Nguyen , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , Richard Weinberger , Anton Ivanov , Johannes Berg , Alexander Viro , Christian Brauner , Jan Kara , Xu Xin , Chengming Zhou , Michal Hocko , Paul Moore , Stephen Smalley , Ondrej Mosnacek , linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-hexagon@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-um@lists.infradead.org, linux-fsdevel@vger.kernel.org, selinux@vger.kernel.org Subject: [PATCH v4 15/25] mm: introduce vma_flags_count() and vma[_flags]_test_single_mask() Date: Fri, 20 Mar 2026 19:38:32 +0000 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" vma_flags_count() determines how many bits are set in VMA flags, using bitmap_weight(). vma_flags_test_single_mask() determines if a vma_flags_t set of flags contains a single flag specified as another vma_flags_t value, or if the sought flag mask is empty, it is defined to return false. This is useful when we want to declare a VMA flag as optionally a single flag in a mask or empty depending on kernel configuration. This allows us to have VM_NONE-like semantics when checking whether the flag is set. In a subsequent patch, we introduce the use of VMA_DROPPABLE of type vma_flags_t using precisely these semantics. It would be actively confusing to use vma_flags_test_any_single_mask() for this (and vma_flags_test_all_mask() is not correct to use here, as it trivially returns true when tested against an empty vma flags mask). We introduce vma_flags_count() to be able to assert that the compared flag mask is singular or empty, checked when CONFIG_DEBUG_VM is enabled. Also update the VMA tests as part of this change. Acked-by: Vlastimil Babka (SUSE) Signed-off-by: Lorenzo Stoakes (Oracle) --- include/linux/mm.h | 46 ++++++++++++++++++++++++++++++ tools/testing/vma/include/custom.h | 6 ---- tools/testing/vma/include/dup.h | 21 ++++++++++++++ tools/testing/vma/vma_internal.h | 6 ++++ 4 files changed, 73 insertions(+), 6 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 47bf9f166924..324b6e8a66fa 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1083,6 +1083,14 @@ static __always_inline vma_flags_t __mk_vma_flags(vm= a_flags_t flags, #define append_vma_flags(flags, ...) __mk_vma_flags(flags, \ COUNT_ARGS(__VA_ARGS__), (const vma_flag_t []){__VA_ARGS__}) =20 +/* Calculates the number of set bits in the specified VMA flags. */ +static __always_inline int vma_flags_count(const vma_flags_t *flags) +{ + const unsigned long *bitmap =3D flags->__vma_flags; + + return bitmap_weight(bitmap, NUM_VMA_FLAG_BITS); +} + /* * Test whether a specific VMA flag is set, e.g.: * @@ -1158,6 +1166,26 @@ static __always_inline bool vma_flags_test_all_mask(= const vma_flags_t *flags, #define vma_flags_test_all(flags, ...) \ vma_flags_test_all_mask(flags, mk_vma_flags(__VA_ARGS__)) =20 +/* + * Helper to test that a flag mask of type vma_flags_t has a SINGLE flag s= et + * (returning false if flagmask has no flags set). + * + * This is defined to make the semantics clearer when testing an optionally + * defined VMA flags mask, e.g.: + * + * if (vma_flags_test_single_mask(&flags, VMA_DROPPABLE)) { ... } + * + * When VMA_DROPPABLE is defined if available, or set to EMPTY_VMA_FLAGS + * otherwise. + */ +static __always_inline bool vma_flags_test_single_mask(const vma_flags_t *= flags, + vma_flags_t flagmask) +{ + VM_WARN_ON_ONCE(vma_flags_count(&flagmask) > 1); + + return vma_flags_test_any_mask(flags, flagmask); +} + /* Set each of the to_set flags in flags, non-atomically. */ static __always_inline void vma_flags_set_mask(vma_flags_t *flags, vma_flags_t to_set) @@ -1286,6 +1314,24 @@ static __always_inline bool vma_test_all_mask(const = struct vm_area_struct *vma, #define vma_test_all(vma, ...) \ vma_test_all_mask(vma, mk_vma_flags(__VA_ARGS__)) =20 +/* + * Helper to test that a flag mask of type vma_flags_t has a SINGLE flag s= et + * (returning false if flagmask has no flags set). + * + * This is useful when a flag needs to be either defined or not depending = upon + * kernel configuration, e.g.: + * + * if (vma_test_single_mask(vma, VMA_DROPPABLE)) { ... } + * + * When VMA_DROPPABLE is defined if available, or set to EMPTY_VMA_FLAGS + * otherwise. + */ +static __always_inline bool +vma_test_single_mask(const struct vm_area_struct *vma, vma_flags_t flagmas= k) +{ + return vma_flags_test_single_mask(&vma->flags, flagmask); +} + /* * Helper to set all VMA flags in a VMA. * diff --git a/tools/testing/vma/include/custom.h b/tools/testing/vma/include= /custom.h index 2c498e713fbd..b7d9eb0a44e4 100644 --- a/tools/testing/vma/include/custom.h +++ b/tools/testing/vma/include/custom.h @@ -15,12 +15,6 @@ extern unsigned long dac_mmap_min_addr; #define dac_mmap_min_addr 0UL #endif =20 -#define VM_WARN_ON(_expr) (WARN_ON(_expr)) -#define VM_WARN_ON_ONCE(_expr) (WARN_ON_ONCE(_expr)) -#define VM_WARN_ON_VMG(_expr, _vmg) (WARN_ON(_expr)) -#define VM_BUG_ON(_expr) (BUG_ON(_expr)) -#define VM_BUG_ON_VMA(_expr, _vma) (BUG_ON(_expr)) - #define TASK_SIZE ((1ul << 47)-PAGE_SIZE) =20 /* diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/du= p.h index f9fe07a8a443..244ee02dc21d 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -905,6 +905,13 @@ static __always_inline vma_flags_t __mk_vma_flags(vma_= flags_t flags, #define append_vma_flags(flags, ...) __mk_vma_flags(flags, \ COUNT_ARGS(__VA_ARGS__), (const vma_flag_t []){__VA_ARGS__}) =20 +static __always_inline int vma_flags_count(const vma_flags_t *flags) +{ + const unsigned long *bitmap =3D flags->__vma_flags; + + return bitmap_weight(bitmap, NUM_VMA_FLAG_BITS); +} + static __always_inline bool vma_flags_test(const vma_flags_t *flags, vma_flag_t bit) { @@ -952,6 +959,14 @@ static __always_inline bool vma_flags_test_all_mask(co= nst vma_flags_t *flags, #define vma_flags_test_all(flags, ...) \ vma_flags_test_all_mask(flags, mk_vma_flags(__VA_ARGS__)) =20 +static __always_inline bool vma_flags_test_single_mask(const vma_flags_t *= flags, + vma_flags_t flagmask) +{ + VM_WARN_ON_ONCE(vma_flags_count(&flagmask) > 1); + + return vma_flags_test_any_mask(flags, flagmask); +} + static __always_inline void vma_flags_set_mask(vma_flags_t *flags, vma_fla= gs_t to_set) { unsigned long *bitmap =3D flags->__vma_flags; @@ -1031,6 +1046,12 @@ static __always_inline bool vma_test_all_mask(const = struct vm_area_struct *vma, #define vma_test_all(vma, ...) \ vma_test_all_mask(vma, mk_vma_flags(__VA_ARGS__)) =20 +static __always_inline bool +vma_test_single_mask(const struct vm_area_struct *vma, vma_flags_t flagmas= k) +{ + return vma_flags_test_single_mask(&vma->flags, flagmask); +} + static __always_inline void vma_set_flags_mask(struct vm_area_struct *vma, vma_flags_t flags) { diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_inter= nal.h index 0e1121e2ef23..e12ab2c80f95 100644 --- a/tools/testing/vma/vma_internal.h +++ b/tools/testing/vma/vma_internal.h @@ -51,6 +51,12 @@ typedef unsigned long pgprotval_t; typedef struct pgprot { pgprotval_t pgprot; } pgprot_t; typedef __bitwise unsigned int vm_fault_t; =20 +#define VM_WARN_ON(_expr) (WARN_ON(_expr)) +#define VM_WARN_ON_ONCE(_expr) (WARN_ON_ONCE(_expr)) +#define VM_WARN_ON_VMG(_expr, _vmg) (WARN_ON(_expr)) +#define VM_BUG_ON(_expr) (BUG_ON(_expr)) +#define VM_BUG_ON_VMA(_expr, _vma) (BUG_ON(_expr)) + #include "include/stubs.h" #include "include/dup.h" #include "include/custom.h" --=20 2.53.0