| Message ID | 20200415004353.130248-7-walken@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add a new mmap locking API wrapping mmap_sem calls | expand |
On Tue, Apr 14, 2020 at 05:43:49PM -0700, Michel Lespinasse wrote: > Add API for nested write locks and convert the few call sites doing that. > > Signed-off-by: Michel Lespinasse <walken@google.com> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
On Tue, Apr 14, 2020 at 05:43:49PM -0700, Michel Lespinasse wrote: > @@ -47,7 +48,7 @@ static inline void activate_mm(struct mm_struct *old, struct mm_struct *new) > * when the new ->mm is used for the first time. > */ > __switch_mm(&new->context.id); > - down_write_nested(&new->mmap_sem, 1); > + mmap_write_lock_nested(new, 1); This should have already been using SINGLE_DEPTH_NESTING. 1 is uninformative.
On Mon, Apr 20, 2020 at 12:33 PM Matthew Wilcox <willy@infradead.org> wrote: > > On Tue, Apr 14, 2020 at 05:43:49PM -0700, Michel Lespinasse wrote: > > @@ -47,7 +48,7 @@ static inline void activate_mm(struct mm_struct *old, struct mm_struct *new) > > * when the new ->mm is used for the first time. > > */ > > __switch_mm(&new->context.id); > > - down_write_nested(&new->mmap_sem, 1); > > + mmap_write_lock_nested(new, 1); > > This should have already been using SINGLE_DEPTH_NESTING. 1 is > uninformative. Sure, I can change that. Note, all mmap_write_lock_nested call sites use single depth nesting, so I'm not entirely sure if the argument should be passed to mmap_write_lock_nested in the first place ?
diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h index 62262c5c7785..07e1cb53a89f 100644 --- a/arch/um/include/asm/mmu_context.h +++ b/arch/um/include/asm/mmu_context.h @@ -8,6 +8,7 @@ #include <linux/sched.h> #include <linux/mm_types.h> +#include <linux/mmap_lock.h> #include <asm/mmu.h> @@ -47,7 +48,7 @@ static inline void activate_mm(struct mm_struct *old, struct mm_struct *new) * when the new ->mm is used for the first time. */ __switch_mm(&new->context.id); - down_write_nested(&new->mmap_sem, 1); + mmap_write_lock_nested(new, 1); uml_setup_stubs(new); mmap_write_unlock(new); } diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h index 8b5a3cd56118..9d34b0690403 100644 --- a/include/linux/mmap_lock.h +++ b/include/linux/mmap_lock.h @@ -11,6 +11,11 @@ static inline void mmap_write_lock(struct mm_struct *mm) down_write(&mm->mmap_sem); } +static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass) +{ + down_write_nested(&mm->mmap_sem, subclass); +} + static inline int mmap_write_lock_killable(struct mm_struct *mm) { return down_write_killable(&mm->mmap_sem); diff --git a/kernel/fork.c b/kernel/fork.c index 9a2511a6714f..bdb5ec3574eb 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -499,7 +499,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, /* * Not linked in yet - no deadlock potential: */ - down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); + mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING); /* No ordering required: file already has been exposed. */ RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
Add API for nested write locks and convert the few call sites doing that. Signed-off-by: Michel Lespinasse <walken@google.com> --- arch/um/include/asm/mmu_context.h | 3 ++- include/linux/mmap_lock.h | 5 +++++ kernel/fork.c | 2 +- 3 files changed, 8 insertions(+), 2 deletions(-)