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Mon, 18 May 2020 13:45:26 +0000 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 04IDjO5P59375632 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 18 May 2020 13:45:24 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E693D42047; Mon, 18 May 2020 13:45:23 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C96E242045; Mon, 18 May 2020 13:45:22 +0000 (GMT) Received: from pomme.local (unknown [9.145.67.24]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 18 May 2020 13:45:22 +0000 (GMT) Subject: Re: [PATCH v5.5 10/10] mmap locking API: rename mmap_sem to mmap_lock To: Michel Lespinasse , Matthew Wilcox Cc: Andrew Morton , linux-mm , LKML , Peter Zijlstra , Vlastimil Babka , Liam Howlett , Jerome Glisse , Davidlohr Bueso , David Rientjes , Hugh Dickins , Ying Han , Jason Gunthorpe , Daniel Jordan References: <20200422001422.232330-1-walken@google.com> <20200422001422.232330-11-walken@google.com> <20200422015829.GR5820@bombadil.infradead.org> <20200423015917.GA13910@bombadil.infradead.org> <20200424012612.GA158937@google.com> <20200424013958.GC158937@google.com> From: Laurent Dufour Message-ID: Date: Mon, 18 May 2020 15:45:22 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200424013958.GC158937@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.676 definitions=2020-05-18_06:2020-05-15,2020-05-18 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 priorityscore=1501 malwarescore=0 mlxscore=0 mlxlogscore=999 impostorscore=0 spamscore=0 clxscore=1015 cotscore=-2147483648 lowpriorityscore=0 adultscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2005180117 Content-Transfer-Encoding: quoted-printable 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: Le 24/04/2020 =C3=A0 03:39, Michel Lespinasse a =C3=A9crit=C2=A0: > Rename the mmap_sem field to mmap_lock. Any new uses of this lock > should now go through the new mmap locking api. The mmap_lock is > still implemented as a rwsem, though this could change in the future. >=20 > Signed-off-by: Michel Lespinasse > --- > arch/ia64/mm/fault.c | 4 +-- > arch/x86/mm/fault.c | 2 +- > drivers/gpu/drm/etnaviv/etnaviv_gem.c | 2 +- > include/linux/mm_types.h | 2 +- > include/linux/mmap_lock.h | 38 +++++++++++++-------------= - > mm/memory.c | 2 +- > mm/mmap.c | 4 +-- > mm/mmu_notifier.c | 2 +- > 8 files changed, 28 insertions(+), 28 deletions(-) >=20 > diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c > index 693f00b117e1..9b95050c2048 100644 > --- a/arch/ia64/mm/fault.c > +++ b/arch/ia64/mm/fault.c > @@ -70,8 +70,8 @@ ia64_do_page_fault (unsigned long address, unsigned l= ong isr, struct pt_regs *re > mask =3D ((((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT) > | (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT)); > =20 > - /* mmap_sem is performance critical.... */ > - prefetchw(&mm->mmap_sem); > + /* mmap_lock is performance critical.... */ > + prefetchw(&mm->mmap_lock); > =20 > /* > * If we're in an interrupt or have no user context, we must not tak= e the fault.. > diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c > index 181f66b9049f..35f530f9dfc0 100644 > --- a/arch/x86/mm/fault.c > +++ b/arch/x86/mm/fault.c > @@ -1522,7 +1522,7 @@ dotraplinkage void > do_page_fault(struct pt_regs *regs, unsigned long hw_error_code, > unsigned long address) > { > - prefetchw(¤t->mm->mmap_sem); > + prefetchw(¤t->mm->mmap_lock); > trace_page_fault_entries(regs, hw_error_code, address); > =20 > if (unlikely(kmmio_fault(regs, address))) > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/et= naviv/etnaviv_gem.c > index dc9ef302f517..701f3995f621 100644 > --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c > @@ -661,7 +661,7 @@ static int etnaviv_gem_userptr_get_pages(struct etn= aviv_gem_object *etnaviv_obj) > struct etnaviv_gem_userptr *userptr =3D &etnaviv_obj->userptr; > int ret, pinned =3D 0, npages =3D etnaviv_obj->base.size >> PAGE_SHI= FT; > =20 > - might_lock_read(¤t->mm->mmap_sem); > + might_lock_read(¤t->mm->mmap_lock); Why not a mm_might_lock_read() new API to hide the mmap_lock, and add it = to the=20 previous patch? > =20 > if (userptr->mm !=3D current->mm) > return -EPERM; > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 4aba6c0c2ba8..d13b90399c16 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -436,7 +436,7 @@ struct mm_struct { > spinlock_t page_table_lock; /* Protects page tables and some > * counters > */ > - struct rw_semaphore mmap_sem; > + struct rw_semaphore mmap_lock; > =20 > struct list_head mmlist; /* List of maybe swapped mm's. These > * are globally strung together off > diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h > index 5bf7cee5d93b..9dc632add390 100644 > --- a/include/linux/mmap_lock.h > +++ b/include/linux/mmap_lock.h > @@ -4,67 +4,67 @@ > #include > =20 > #define MMAP_LOCK_INITIALIZER(name) \ > - .mmap_sem =3D __RWSEM_INITIALIZER(name.mmap_sem), > + .mmap_lock =3D __RWSEM_INITIALIZER(name.mmap_lock), > =20 > static inline void mmap_init_lock(struct mm_struct *mm) > { > - init_rwsem(&mm->mmap_sem); > + init_rwsem(&mm->mmap_lock); > } > =20 > static inline void mmap_write_lock(struct mm_struct *mm) > { > - down_write(&mm->mmap_sem); > + down_write(&mm->mmap_lock); > } > =20 > static inline void mmap_write_lock_nested(struct mm_struct *mm, int s= ubclass) > { > - down_write_nested(&mm->mmap_sem, subclass); > + down_write_nested(&mm->mmap_lock, subclass); > } > =20 > static inline int mmap_write_lock_killable(struct mm_struct *mm) > { > - return down_write_killable(&mm->mmap_sem); > + return down_write_killable(&mm->mmap_lock); > } > =20 > static inline bool mmap_write_trylock(struct mm_struct *mm) > { > - return down_write_trylock(&mm->mmap_sem) !=3D 0; > + return down_write_trylock(&mm->mmap_lock) !=3D 0; > } > =20 > static inline void mmap_write_unlock(struct mm_struct *mm) > { > - up_write(&mm->mmap_sem); > + up_write(&mm->mmap_lock); > } > =20 > static inline void mmap_write_downgrade(struct mm_struct *mm) > { > - downgrade_write(&mm->mmap_sem); > + downgrade_write(&mm->mmap_lock); > } > =20 > static inline void mmap_read_lock(struct mm_struct *mm) > { > - down_read(&mm->mmap_sem); > + down_read(&mm->mmap_lock); > } > =20 > static inline int mmap_read_lock_killable(struct mm_struct *mm) > { > - return down_read_killable(&mm->mmap_sem); > + return down_read_killable(&mm->mmap_lock); > } > =20 > static inline bool mmap_read_trylock(struct mm_struct *mm) > { > - return down_read_trylock(&mm->mmap_sem) !=3D 0; > + return down_read_trylock(&mm->mmap_lock) !=3D 0; > } > =20 > static inline void mmap_read_unlock(struct mm_struct *mm) > { > - up_read(&mm->mmap_sem); > + up_read(&mm->mmap_lock); > } > =20 > static inline bool mmap_read_trylock_non_owner(struct mm_struct *mm) > { > - if (down_read_trylock(&mm->mmap_sem)) { > - rwsem_release(&mm->mmap_sem.dep_map, _RET_IP_); > + if (down_read_trylock(&mm->mmap_lock)) { > + rwsem_release(&mm->mmap_lock.dep_map, _RET_IP_); > return true; > } > return false; > @@ -72,19 +72,19 @@ static inline bool mmap_read_trylock_non_owner(stru= ct mm_struct *mm) > =20 > static inline void mmap_read_unlock_non_owner(struct mm_struct *mm) > { > - up_read_non_owner(&mm->mmap_sem); > + up_read_non_owner(&mm->mmap_lock); > } > =20 > static inline void mmap_assert_locked(struct mm_struct *mm) > { > - VM_BUG_ON_MM(!lockdep_is_held_type(&mm->mmap_sem, -1), mm); > - VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm); > + VM_BUG_ON_MM(!lockdep_is_held_type(&mm->mmap_lock, -1), mm); > + VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm); > } > =20 > static inline void mmap_assert_write_locked(struct mm_struct *mm) > { > - VM_BUG_ON_MM(!lockdep_is_held_type(&mm->mmap_sem, 0), mm); > - VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm); > + VM_BUG_ON_MM(!lockdep_is_held_type(&mm->mmap_lock, 0), mm); > + VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm); > } > =20 > #endif /* _LINUX_MMAP_LOCK_H */ > diff --git a/mm/memory.c b/mm/memory.c > index 20f98ea8968e..c2963e7affa9 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -4811,7 +4811,7 @@ void __might_fault(const char *file, int line) > __might_sleep(file, line, 0); > #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) > if (current->mm) > - might_lock_read(¤t->mm->mmap_sem); > + might_lock_read(¤t->mm->mmap_lock); > #endif > } > EXPORT_SYMBOL(__might_fault); > diff --git a/mm/mmap.c b/mm/mmap.c > index 2f4ffccc5972..80a47031d5db 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -3474,7 +3474,7 @@ static void vm_lock_anon_vma(struct mm_struct *mm= , struct anon_vma *anon_vma) > * The LSB of head.next can't change from under us > * because we hold the mm_all_locks_mutex. > */ > - down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem); > + down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock); > /* > * We can safely modify head.next after taking the > * anon_vma->root->rwsem. If some other vma in this mm shares > @@ -3504,7 +3504,7 @@ static void vm_lock_mapping(struct mm_struct *mm,= struct address_space *mapping) > */ > if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) > BUG(); > - down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem); > + down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock); > } > } > =20 > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > index 24eb9d1ed0a7..2f348b6c9c9a 100644 > --- a/mm/mmu_notifier.c > +++ b/mm/mmu_notifier.c > @@ -983,7 +983,7 @@ int mmu_interval_notifier_insert(struct mmu_interva= l_notifier *interval_sub, > struct mmu_notifier_subscriptions *subscriptions; > int ret; > =20 > - might_lock(&mm->mmap_sem); > + might_lock(&mm->mmap_lock); Same here with a new mm_might_lock()? > =20 > subscriptions =3D smp_load_acquire(&mm->notifier_subscriptions); > if (!subscriptions || !subscriptions->has_itree) { >=20