multifd: Fix a race on reading MultiFDPages_t.block

In multifd_queue_page() MultiFDPages_t.block is checked twice.
Between the two checks, MultiFDPages_t.block may be reset to NULL
by multifd thread. This lead to the 2nd check always true then a
redundant page submitted to multifd thread again.

Signed-off-by: Zhenzhong Duan <>
Reviewed-by: Juan Quintela <>
Signed-off-by: Juan Quintela <>
1 file changed