mmap locking API: convert nested write lock sites (aaa2cc56) · Commits · 戴 / test

Add API for nested write locks and convert the few call sites doing that. Signed-off-by:

Michel Lespinasse <walken@google.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Reviewed-by:

Daniel Jordan <daniel.m.jordan@oracle.com> Reviewed-by:

Laurent Dufour <ldufour@linux.ibm.com> Reviewed-by:

Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-7-walken@google.com Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

arch/um/include/asm/mmu_context.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -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, SINGLE_DEPTH_NESTING);
		uml_setup_stubs(new);
		mmap_write_unlock(new);
		}

include/linux/mmap_lock.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -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);

kernel/fork.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -501,7 +501,7 @@ 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));

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