From 4a23717a236b2ab31efb1651f586126789fc997f Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Fri, 12 Dec 2014 16:54:30 -0800 Subject: [PATCH] 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 Acked-by: Srikar Dronamraju Acked-by: "Kirill A. Shutemov" Cc: Oleg Nesterov Acked-by: Hugh Dickins Acked-by: Peter Zijlstra (Intel) Cc: Rik van Riel Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/events/uprobes.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 1901dbfa7ce0..995a95f61a19 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -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; -- 2.20.1