Eric Lee / smarc-ti-linux-kernel

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Commit 30002ed2e41830ec03ec3e577ad83ac6b188f96e

Authored by Nick Piggin
Committed by Linus Torvalds
1 parent 652ea69536
Exists in master and in 20 other branches dlt-processor-sdk-linux-03.00.00.04, newt-ti-linux-3.12.y, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.12.10, smarc-ti-linux-3.12.y, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.12.y, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

mm: readahead scan lockless 

radix_tree_next_hole() is implemented as a series of radix_tree_lookup()s.
So it can be called locklessly, under rcu_read_lock().

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 3 additions and 3 deletions Side-by-side Diff

... ... @@ -382,9 +382,9 @@
382 382 if (hit_readahead_marker) {
383 383 pgoff_t start;
384 384  
385   - read_lock_irq(&mapping->tree_lock);
386   - start = radix_tree_next_hole(&mapping->page_tree, offset, max+1);
387   - read_unlock_irq(&mapping->tree_lock);
  385 + rcu_read_lock();
  386 + start = radix_tree_next_hole(&mapping->page_tree, offset,max+1);
  387 + rcu_read_unlock();
388 388  
389 389 if (!start || start - offset > max)
390 390 return 0;