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sfid-20241028_142835_761528_A79ED2AB X-CRM114-Status: GOOD ( 25.70 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Oct 28, 2024 at 09:05:33PM +0000, Mark Brown wrote: > On Mon, Oct 28, 2024 at 08:43:08PM +0000, Lorenzo Stoakes wrote: > > > +/* > > + * We check VMA flag validity early in the mmap() process, however this can > > + * cause issues for arm64 when using MTE, which requires that it be used with > > + * shmem and in this instance and only then is VM_MTE_ALLOWED set permitting > > + * this operation. > > + * > > + * To avoid having to tear down a partially complete mapping we do this ahead of > > + * time. > > + */ > > +static vm_flags_t arch_adjust_flags(struct file *file, vm_flags_t vm_flags) > > +{ > > + if (!IS_ENABLED(CONFIG_ARM64)) > > + return vm_flags; > > + > > + if (shmem_file(file)) > > + return vm_flags | VM_MTE_ALLOWED; > > +} > > This doesn't build: > > mm/mmap.c:1595:1: error: non-void function does not return a value in all control paths [-Werror,-Wreturn-type] > 1595 | } > | ^ Doh that'll teach me for rushing this... > > with that corrected: > > diff --git a/mm/mmap.c b/mm/mmap.c > index d1ab4301c671..cea051c5fef3 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -1587,11 +1587,10 @@ static unsigned long __mmap_region(struct file *file, unsigned long addr, > */ > static vm_flags_t arch_adjust_flags(struct file *file, vm_flags_t vm_flags) > { > - if (!IS_ENABLED(CONFIG_ARM64)) > - return vm_flags; > + if (IS_ENABLED(CONFIG_ARM64) && shmem_file(file)) > + vm_flags |= VM_MTE_ALLOWED; > > - if (shmem_file(file)) > - return vm_flags | VM_MTE_ALLOWED; > + return vm_flags; > } > > unsigned long mmap_region(struct file *file, unsigned long addr, > > the relevant tests all pass for me. > > Tested-by: Mark Brown Thanks! > > I'd have expected arch_adjust_flags() to be something overridden by the > arch headers (probably like arch_calc_vm_prot_bits() and friends), but > if this is juat a short lived fix it's probably not worth the trouble. Yeah this is just a sample solution that I had put together when Linus suggested a sensible alternative which I'll code up... Good to confirm this is definitely the issue thanks for testing!