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Date: Wed, 8 Feb 2023 01:48:39 +0000 From: Hyeonggon Yoo <42.hyeyoo@...il.com> To: Suren Baghdasaryan <surenb@...gle.com> Cc: akpm@...ux-foundation.org, michel@...pinasse.org, jglisse@...gle.com, mhocko@...e.com, vbabka@...e.cz, hannes@...xchg.org, mgorman@...hsingularity.net, dave@...olabs.net, willy@...radead.org, liam.howlett@...cle.com, peterz@...radead.org, ldufour@...ux.ibm.com, paulmck@...nel.org, mingo@...hat.com, will@...nel.org, luto@...nel.org, songliubraving@...com, peterx@...hat.com, david@...hat.com, dhowells@...hat.com, hughd@...gle.com, bigeasy@...utronix.de, kent.overstreet@...ux.dev, punit.agrawal@...edance.com, lstoakes@...il.com, peterjung1337@...il.com, rientjes@...gle.com, axelrasmussen@...gle.com, joelaf@...gle.com, minchan@...gle.com, rppt@...nel.org, jannh@...gle.com, shakeelb@...gle.com, tatashin@...gle.com, edumazet@...gle.com, gthelen@...gle.com, gurua@...gle.com, arjunroy@...gle.com, soheil@...gle.com, leewalsh@...gle.com, posk@...gle.com, linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org, x86@...nel.org, linux-kernel@...r.kernel.org, kernel-team@...roid.com Subject: Re: [PATCH v4 2/7] mm: introduce vma->vm_flags wrapper functions 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 <surenb@...gle.com> > Reviewed-by: Davidlohr Bueso <dave@...olabs.net> > Acked-by: Michal Hocko <mhocko@...e.com> > Acked-by: Mel Gorman <mgorman@...hsingularity.net> > --- > 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@...il.com> > -- > 2.39.1 > >
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