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It tries to check against all zeros and looped for quite a few times. However after that we'll verify the same page with count_verify, while count_verify can never be zero. So it means if it's a zero page we'll detect it anyways with below code. There's yet another place we conditionally check the fault flag - just do it unconditionally. Link: https://lkml.kernel.org/r/20210310004511.51996-4-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 9c42d387952986b4159ce304a14771a0534469b3 https: //git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1392478/ Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: Iee4e4fa10db0b2a01cb4804087275d2714e477b4