Following the recent discussions here's another take at initializing pages and heap objects with zeroes. This is needed to prevent possible information leaks and make the control-flow bugs that depend on uninitialized values more deterministic. The patchset introduces a new boot option, init_allocations, which makes page allocator and SL[AOU]B initialize newly allocated memory. init_allocations=0 doesn't (hopefully) add any overhead to the allocation fast path (no noticeable slowdown on hackbench). With only the the first of the proposed patches the slowdown numbers are: - 1.1% (stdev 0.2%) sys time slowdown building Linux kernel - 3.1% (stdev 0.3%) sys time slowdown on af_inet_loopback benchmark - 9.4% (stdev 0.5%) sys time slowdown on hackbench The second patch introduces a GFP flag that allows to disable initialization for certain allocations. The third page is an example of applying it to af_unix.c, which helps hackbench greatly. Slowdown numbers for the whole patchset are: - 1.8% (stdev 0.8%) on kernel build - 6.5% (stdev 0.2%) on af_inet_loopback - 0.12% (stdev 0.6%) on hackbench Alexander Potapenko (3): mm: security: introduce the init_allocations=1 boot option gfp: mm: introduce __GFP_NOINIT net: apply __GFP_NOINIT to AF_UNIX sk_buff allocations drivers/infiniband/core/uverbs_ioctl.c | 2 +- include/linux/gfp.h | 6 ++++- include/linux/mm.h | 8 +++++++ include/linux/slab_def.h | 1 + include/linux/slub_def.h | 1 + include/net/sock.h | 5 +++++ kernel/kexec_core.c | 4 ++-- mm/dmapool.c | 2 +- mm/page_alloc.c | 18 ++++++++++++++- mm/slab.c | 14 ++++++------ mm/slab.h | 1 + mm/slab_common.c | 15 +++++++++++++ mm/slob.c | 3 ++- mm/slub.c | 9 ++++---- net/core/sock.c | 31 +++++++++++++++++++++----- net/unix/af_unix.c | 13 ++++++----- 16 files changed, 104 insertions(+), 29 deletions(-) -- 2.21.0.392.gf8f6787159e-goog
