On Wed, 2011-02-23 at 21:35 -0800, Hugh Dickins wrote: > Callers of find_get_pages(), or its wrapper pagevec_lookup() - notably > truncate_inode_pages_range() - stop looking further when it returns 0. > > But if an interrupt comes just after its radix_tree_gang_lookup_slot(), > especially if we have preemptible RCU enabled, isn't it conceivable > that all 14 pages returned could be removed from the page cache by > shrink_page_list(), before find_get_pages() gets to process them? So > causing it to return 0 although there may be plenty more pages beyond. > > Make find_get_pages() and find_get_pages_tag() check for this unlikely > case, and restart should it occur; but callers of find_get_pages_contig() > have no such expectation, it's okay for that to return 0 early. > > I have not seen this in practice, just worried by the possibility. > > Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href