Re: [PATCH v2 1/6] mm: introduce vma->vm_flags modifier functions
From: Suren Baghdasaryan <surenb@google.com>
Date: 2023-01-25 16:50:49
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alsa-devel, amd-gfx, bpf, dri-devel, intel-gfx, kexec, kvm, linux-acpi, linux-arch, linux-arm-msm, linux-crypto, linux-ext4, linux-fbdev, linux-fsdevel, linux-media, linux-mediatek, linux-mm, linux-perf-users, linux-rdma, linux-s390, linux-samsung-soc, linux-scsi, linux-staging, linux-tegra, linux-um, linux-usb, linux-xfs, linuxppc-dev, lkml, loongarch, netdev, nvdimm, selinux, sparclinux, target-devel, xen-devel
On Wed, Jan 25, 2023 at 1:10 AM Peter Zijlstra [off-list ref] wrote:
On Wed, Jan 25, 2023 at 12:38:46AM -0800, Suren Baghdasaryan wrote:quoted
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 2d6d790d9bed..6c7c70bf50dd 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h@@ -491,7 +491,13 @@ struct vm_area_struct { * See vmf_insert_mixed_prot() for discussion. */ pgprot_t vm_page_prot; - unsigned long vm_flags; /* Flags, see mm.h. */ + + /* + * Flags, see mm.h. + * WARNING! Do not modify directly. + * Use {init|reset|set|clear|mod}_vm_flags() functions instead. + */ + unsigned long vm_flags;We have __private and ACCESS_PRIVATE() to help with enforcing this.
Thanks for pointing this out, Peter! I guess for that I'll need to convert all read accesses and provide get_vm_flags() too? That will cause some additional churt (a quick search shows 801 hits over 248 files) but maybe it's worth it? I think Michal suggested that too in another patch. Should I do that while we are at it?