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Wed, 28 Jan 2026 10:52:49 -0800 (PST) MIME-Version: 1.0 References: <47eafa10-6d13-4324-830a-2e7cf4e67f2b@suse.cz> <6444753e-1df7-4732-912a-0ea441f76cb1@lucifer.local> <425e3040-0522-4af1-a7b9-c9ad04e017e8@lucifer.local> In-Reply-To: From: Suren Baghdasaryan Date: Wed, 28 Jan 2026 10:52:37 -0800 X-Gm-Features: AZwV_QgZBjbER74dI9m_uPvunquAKGJLY8LFOmekpfhxdXBjBkDVXkOvnrwg-7c Message-ID: Subject: Re: [PATCH v4 08/10] mm/vma: improve and document __is_vma_write_locked() To: Vlastimil Babka Cc: Lorenzo Stoakes , Andrew Morton , David Hildenbrand , "Liam R . Howlett" , Mike Rapoport , Michal Hocko , Shakeel Butt , Jann Horn , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, Peter Zijlstra , Ingo Molnar , Will Deacon , Boqun Feng , Waiman Long , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam11 X-Stat-Signature: usjkcx4838d7f5x1zxaak3qpi3kkbne3 X-Rspam-User: X-Rspamd-Queue-Id: E6DE2140009 X-HE-Tag: 1769626370-701365 X-HE-Meta: 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 RwGS8Ek3 E6x6LBG6IMCeGBKK3hu6hcIV8WE0/DP2Ih8t5RoiHDOnSJfFsFnC9YoPuPdG64H/C8erHReJrU/4Exl2/SC/NakqZ6HzBfwHf6P5KkATI45RQ0P6PYZ1/hjy+C5PRlj4OGkaNtZutZViMO64ZvJhGaj39lhaYHT/7TVAM1BFn0wabRaYanRbBPqnPVTYuVpC27VS2X99xB8vq/KG4rQn2YWy+ndsJxYpFxGWshXofwz2rsOuU9Xh0hrdZl2BccAVvDbw0z69jNyVMGKaZpUsfW4D1WvA5h071SKInaN1f1CnF/IMZbWUvmUoPjwu1xNBUIGzhOvYTAdlENCDLAxM1jLKuQWdGWCpU2WPC X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jan 28, 2026 at 5:01=E2=80=AFAM Vlastimil Babka wr= ote: > > On 1/28/26 12:51, Lorenzo Stoakes wrote: > >> > >> > > >> > Thanks! > >> > > >> > > > >> > > Few nits: > >> > > > >> > > > --- > >> > > > include/linux/mmap_lock.h | 44 ++++++++++++++++++++++----------= ------- > >> > > > 1 file changed, 25 insertions(+), 19 deletions(-) > >> > > > > >> > > > diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock= .h > >> > > > index 678f90080fa6..23bde4bd5a85 100644 > >> > > > --- a/include/linux/mmap_lock.h > >> > > > +++ b/include/linux/mmap_lock.h > >> > > > @@ -258,17 +258,30 @@ static inline void vma_end_read(struct vm_= area_struct *vma) > >> > > > vma_refcount_put(vma); > >> > > > } > >> > > > > >> > > > -/* WARNING! Can only be used if mmap_lock is expected to be wri= te-locked */ > >> > > > -static inline bool __is_vma_write_locked(struct vm_area_struct = *vma, unsigned int *mm_lock_seq) > >> > > > +static inline unsigned int __vma_raw_mm_seqnum(struct vm_area_s= truct *vma) > >> > >> This function returns the mm->mm_lock_seq.sequence attribute of mm, so > >> no real commection to VMA. IMO it's better to rename it into > >> __raw_mm_lock_seqnum(const struct mm_struct *mm) and have the callers > >> pass vma->vm_mm. > > > > Sorry missed these comments. > > > > We are only ever referencing in terms of VMA's, so I think it makes sen= se still > > to pass a VMA ptr, even if it just references vma->vm_mm. > > FWIW I agree. > > > I think the name of the function also makes things pretty clear, given = it's > > called essentially 'VMA['s] raw mm seqnum'. > > > >> > >> > > > { > >> > > > + const struct mm_struct *mm =3D vma->vm_mm; > >> > > > + > >> > > > + /* We must hold an exclusive write lock for this access to b= e valid. */ > >> > > > mmap_assert_write_locked(vma->vm_mm); > >> > >> If for some reason you need to keep this function VMA-centric, then in > >> the above line please s/vma->vm_mm/mm > > > > Ah yeah, maybe if there's a respin? As kinda trivial thing, if that mak= es sense > > to you! Ack. > > > > Cheers, Lorenzo >