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Tue, 07 Feb 2023 17:48:52 -0800 (PST) Date: Wed, 8 Feb 2023 01:48:39 +0000 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, paulmck@kernel.org, mingo@redhat.com, will@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, rppt@kernel.org, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, leewalsh@google.com, posk@google.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v4 2/7] mm: introduce vma->vm_flags wrapper functions Message-ID: References: <20230126193752.297968-1-surenb@google.com> <20230126193752.297968-3-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230126193752.297968-3-surenb@google.com> X-Rspamd-Queue-Id: A1D2480003 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: 4h4h1966j6p47f8ig9h786fmcqm94q3h X-HE-Tag: 1675820935-715331 X-HE-Meta: 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 G43pm431 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 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: On Thu, Jan 26, 2023 at 11:37:47AM -0800, Suren Baghdasaryan wrote: > vm_flags are among VMA attributes which affect decisions like VMA merging > and splitting. Therefore all vm_flags modifications are performed after > taking exclusive mmap_lock to prevent vm_flags updates racing with such > operations. Introduce modifier functions for vm_flags to be used whenever > flags are updated. This way we can better check and control correct > locking behavior during these updates. > > Signed-off-by: Suren Baghdasaryan > Reviewed-by: Davidlohr Bueso > Acked-by: Michal Hocko > Acked-by: Mel Gorman > --- > include/linux/mm.h | 40 ++++++++++++++++++++++++++++++++++++++++ > include/linux/mm_types.h | 10 +++++++++- > 2 files changed, 49 insertions(+), 1 deletion(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 8d636e895ee9..abb31103d060 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -627,6 +627,46 @@ static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm) > INIT_LIST_HEAD(&vma->anon_vma_chain); > } > > +/* Use when VMA is not part of the VMA tree and needs no locking */ > +static inline void vm_flags_init(struct vm_area_struct *vma, > + vm_flags_t flags) > +{ > + ACCESS_PRIVATE(vma, __vm_flags) = flags; > +} > + > +/* Use when VMA is part of the VMA tree and modifications need coordination */ > +static inline void vm_flags_reset(struct vm_area_struct *vma, > + vm_flags_t flags) > +{ > + mmap_assert_write_locked(vma->vm_mm); > + vm_flags_init(vma, flags); > +} > + > +static inline void vm_flags_set(struct vm_area_struct *vma, > + vm_flags_t flags) > +{ > + mmap_assert_write_locked(vma->vm_mm); > + ACCESS_PRIVATE(vma, __vm_flags) |= flags; > +} > + > +static inline void vm_flags_clear(struct vm_area_struct *vma, > + vm_flags_t flags) > +{ > + mmap_assert_write_locked(vma->vm_mm); > + ACCESS_PRIVATE(vma, __vm_flags) &= ~flags; > +} > + > +/* > + * Use only when the order of set/clear operations is unimportant, otherwise > + * use vm_flags_{set|clear} explicitly. > + */ > +static inline void vm_flags_mod(struct vm_area_struct *vma, > + vm_flags_t set, vm_flags_t clear) > +{ > + mmap_assert_write_locked(vma->vm_mm); > + vm_flags_init(vma, (vma->vm_flags | set) & ~clear); > +} > + > static inline void vma_set_anonymous(struct vm_area_struct *vma) > { > vma->vm_ops = NULL; > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 2d6d790d9bed..da983aedb741 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -491,7 +491,15 @@ 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. > + * To modify use vm_flags_{init|reset|set|clear|mod} functions. > + */ > + union { > + const vm_flags_t vm_flags; > + vm_flags_t __private __vm_flags; > + }; > > /* > * For areas with an address space and backing store, Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > -- > 2.39.1 > >