From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> commit f5b07b04e5f090a85d1e96938520f2b2b58e4a8e upstream. If we have to drop the seqcount & rcu lock to perform a krealloc, we have to restart the loop. In doing so, be careful not to lose track of the already acquired exclusive fence. Fixes: fedf54132d24 ("dma-buf: Restart reservation_object_get_fences_rcu() after writes") Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> Cc: Christian König <christian.koenig@xxxxxxx> Cc: Alex Deucher <alexander.deucher@xxxxxxx> Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx #v4.10 Reviewed-by: Christian König <christian.koenig@xxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20190604125323.21396-1-chris@xxxxxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/dma-buf/reservation.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/drivers/dma-buf/reservation.c +++ b/drivers/dma-buf/reservation.c @@ -394,6 +394,10 @@ int reservation_object_get_fences_rcu(st GFP_NOWAIT | __GFP_NOWARN); if (!nshared) { rcu_read_unlock(); + + dma_fence_put(fence_excl); + fence_excl = NULL; + nshared = krealloc(shared, sz, GFP_KERNEL); if (nshared) { shared = nshared;