Commit 4a23717a authored Dec 12, 2014 by Davidlohr Bueso Committed by Linus Torvalds Dec 13, 2014

uprobes: share the i_mmap_rwsem



Both register and unregister call build_map_info() in order to create the
list of mappings before installing or removing breakpoints for every mm
which maps file backed memory.  As such, there is no reason to hold the
i_mmap_rwsem exclusively, so share it and allow concurrent readers to
build the mapping data.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 3dec0ba0

kernel/events/uprobes.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -724,7 +724,7 @@ build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
		int more = 0;

		again:
		i_mmap_lock_write(mapping);
		i_mmap_lock_read(mapping);
		vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
		if (!valid_vma(vma, is_register))
		continue;
		@@ -755,7 +755,7 @@ build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
		info->mm = vma->vm_mm;
		info->vaddr = offset_to_vaddr(vma, offset);
		}
		i_mmap_unlock_write(mapping);
		i_mmap_unlock_read(mapping);

		if (!more)
		goto out;

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