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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Hugh Dickins , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , Kees Cook , Jaroslav Kysela , Takashi Iwai , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, dri-devel@lists.freedesktop.org, etnaviv@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-rockchip@lists.infradead.org, linux-tegra@vger.kernel.org, virtualization@lists.linux.dev, intel-xe@lists.freedesktop.org, xen-devel@lists.xenproject.org, linux-fbdev@vger.kernel.org, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-sound@vger.kernel.org Subject: Re: [PATCH 01/13] mm: introduce vma_flags_can_grow() and vma_can_grow() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: fpft5xxczpsy3kgyhj8wszo71i3oxthz X-Rspam-User: X-Rspamd-Queue-Id: 3588318000A X-Rspamd-Server: rspam02 X-HE-Tag: 1782805157-106637 X-HE-Meta: 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 kDyf6n0n j9BcilQsxTuup0hg4E937UM/r37ZK/iDLFO5z9Dbwywl7KKb0zCUG8tKUJGnNHT/cYybWRIc3Hng1Bq1vKZrV+a2QVoGW8tXo20Z/W/Pla3frjnrqCpsRb3JAJoBV2XX6ky300HwITVJXnifMgs1Pw4QQjrLi0xrxb8xbDWUhpA22dlDwHxSPFdbj4G+6q9dBRmZBu3MJW5KY9tYeuOybqhJIzg+RNN76AxnxV5dOPMnKxFp72eqpsJOzGKSj6PI2g2Del4638P48n+NTK/H//mFxsSRZ1zXYrAjOLOF6SyPY/28TZChVmzVkukfEhB5oCJqu Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jun 29, 2026 at 04:26:18PM -0400, Zi Yan wrote: > On Mon Jun 29, 2026 at 3:25 PM EDT, Lorenzo Stoakes wrote: > > These test whether the VMA has stack sematics, i.e. is able to grow upwards > > or downwards depending on the architecture. > > > > In order to account for arches which do not support upward-growing stacks, > > introduce VMA_GROWSUP whose definition depends on the architecture > > supporting it, and use vma_flags_test_single_mask() in vma_flags_can_grow() > > to account for this. > > > > Update the VMA userland tests to reflect the changes > > > > No functional change intended. > > > > Signed-off-by: Lorenzo Stoakes > > --- > > include/linux/mm.h | 21 ++++++++++++++++++--- > > tools/testing/vma/include/dup.h | 4 ++++ > > 2 files changed, 22 insertions(+), 3 deletions(-) > > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index 868b2334bff3..cf7df1569052 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -472,6 +472,7 @@ enum { > > #define VM_SAO INIT_VM_FLAG(SAO) > > #elif defined(CONFIG_PARISC) > > #define VM_GROWSUP INIT_VM_FLAG(GROWSUP) > > +#define VMA_GROWSUP mk_vma_flags(VMA_GROWSUP_BIT) > > #elif defined(CONFIG_SPARC64) > > #define VM_SPARC_ADI INIT_VM_FLAG(SPARC_ADI) > > #define VM_ARCH_CLEAR INIT_VM_FLAG(ARCH_CLEAR) > > @@ -483,6 +484,7 @@ enum { > > #endif > > #ifndef VM_GROWSUP > > #define VM_GROWSUP VM_NONE > > +#define VMA_GROWSUP EMPTY_VMA_FLAGS > > #endif > > #ifdef CONFIG_ARM64_MTE > > #define VM_MTE INIT_VM_FLAG(MTE) > > @@ -1563,11 +1565,24 @@ static inline bool vma_is_initial_stack(const struct vm_area_struct *vma) > > vma->vm_end >= vma->vm_mm->start_stack; > > } > > > > -static inline bool vma_is_temporary_stack(const struct vm_area_struct *vma) > > +static inline bool vma_flags_can_grow(const vma_flags_t *flags) > > { > > - int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP); > > + if (vma_flags_test_single_mask(flags, VMA_GROWSUP)) > > + return true; > > + if (vma_flags_test(flags, VMA_GROWSDOWN_BIT)) > > + return true; > > + > > + return false; > > +} > > > > - if (!maybe_stack) > > +static inline bool vma_can_grow(const struct vm_area_struct *vma) > > +{ > > + return vma_flags_can_grow(&vma->flags); > > Would it save vma_flags_can_grow() if we do below? > > return vma_test(vma, VMA_GROWSDOWN_BIT) || vma_test_single_mask(vma, VMA_GROWSUP); > > I find these two functions when I am reading mm.h. Yeah but we require vma_flags_can_grow() for code in mmap.c, the majority of checks of this have only vma_flags_t to work with not a VMA :) > > > +} > > + > > +static inline bool vma_is_temporary_stack(const struct vm_area_struct *vma) > > +{ > > + if (!vma_can_grow(vma)) > > return false; > > > > if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) == > > diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h > > index 5d7d0afd7765..6f5bcd7fbcd8 100644 > > --- a/tools/testing/vma/include/dup.h > > +++ b/tools/testing/vma/include/dup.h > > @@ -245,8 +245,10 @@ enum { > > #define VM_STACK INIT_VM_FLAG(STACK) > > #ifdef CONFIG_STACK_GROWS_UP > > #define VM_STACK_EARLY INIT_VM_FLAG(STACK_EARLY) > > +#define VMA_STACK_EARLY mk_vma_flags(VMA_STACK_EARLY_BIT) > > #else > > #define VM_STACK_EARLY VM_NONE > > +#define VMA_STACK_EARLY EMPTY_VMA_FLAGS > > #endif > > #ifdef CONFIG_ARCH_HAS_PKEYS > > #define VM_PKEY_SHIFT ((__force int)VMA_HIGH_ARCH_0_BIT) > > @@ -315,6 +317,8 @@ enum { > > > > /* Bits set in the VMA until the stack is in its final location */ > > #define VM_STACK_INCOMPLETE_SETUP (VM_RAND_READ | VM_SEQ_READ | VM_STACK_EARLY) > > +#define VMA_STACK_INCOMPLETE_SETUP append_vma_flags( \ > > + VMA_STACK_EARLY, VMA_RAND_READ_BIT, VMA_SEQ_READ_BIT) > > > > #define TASK_EXEC_BIT ((current->personality & READ_IMPLIES_EXEC) ? \ > > VM_EXEC_BIT : VM_READ_BIT) > > Why are VMA_STACK_EARLY and VMA_STACK_INCOMPLETE_SETUP added here but > not in mm.h? Yeah urgh oops my bad. It doesn't really break anything but I'll fix it if a respin is needed... > > > -- > Best Regards, > Yan, Zi > Thanks, Lorenzo