From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 65/93] mmap locking API: convert nested write lock sites Date: Mon, 08 Jun 2020 21:33:33 -0700 Message-ID: <20200609043333.jlWUJ02cB%akpm@linux-foundation.org> References: <20200608212922.5b7fa74ca3f4e2444441b7f9@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:57120 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725894AbgFIEdg (ORCPT ); Tue, 9 Jun 2020 00:33:36 -0400 In-Reply-To: <20200608212922.5b7fa74ca3f4e2444441b7f9@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, daniel.m.jordan@oracle.com, dbueso@suse.de, hughd@google.com, jgg@ziepe.ca, jglisse@redhat.com, jhubbard@nvidia.com, ldufour@linux.ibm.com, Liam.Howlett@oracle.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, peterz@infradead.org, rientjes@google.com, torvalds@linux-foundation.org, vbabka@suse.cz, walken@google.com, willy@infradead.org, yinghan@google.com From: Michel Lespinasse Subject: mmap locking API: convert nested write lock sites Add API for nested write locks and convert the few call sites doing that. Link: http://lkml.kernel.org/r/20200520052908.204642-7-walken@google.com Signed-off-by: Michel Lespinasse Reviewed-by: Daniel Jordan Reviewed-by: Laurent Dufour Reviewed-by: Vlastimil Babka Cc: Davidlohr Bueso Cc: David Rientjes Cc: Hugh Dickins Cc: Jason Gunthorpe Cc: Jerome Glisse Cc: John Hubbard Cc: Liam Howlett Cc: Matthew Wilcox Cc: Peter Zijlstra Cc: Ying Han Signed-off-by: Andrew Morton --- 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(-) --- a/arch/um/include/asm/mmu_context.h~mmap-locking-api-convert-nested-write-lock-sites +++ a/arch/um/include/asm/mmu_context.h @@ -8,6 +8,7 @@ #include #include +#include #include @@ -47,7 +48,7 @@ static inline void activate_mm(struct mm * 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, SINGLE_DEPTH_NESTING); uml_setup_stubs(new); mmap_write_unlock(new); } --- a/include/linux/mmap_lock.h~mmap-locking-api-convert-nested-write-lock-sites +++ a/include/linux/mmap_lock.h @@ -11,6 +11,11 @@ static inline void mmap_write_lock(struc 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); --- a/kernel/fork.c~mmap-locking-api-convert-nested-write-lock-sites +++ a/kernel/fork.c @@ -501,7 +501,7 @@ static __latent_entropy int dup_mmap(str /* * 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)); _