From: Alexei Starovoitov <ast@kernel.org>
Date: Wed, 15 Feb 2023 23:40:06 +0000 (-0800)
Subject: Merge branch 'Use __GFP_ZERO in bpf memory allocator'
X-Git-Tag: v6.6.17~5509^2~13^2~22
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3538a0fbbd81bc131afe48b4cf02895735944359;p=platform%2Fkernel%2Flinux-rpi.git

Merge branch 'Use __GFP_ZERO in bpf memory allocator'

Hou Tao says:

====================

From: Hou Tao <houtao1@huawei.com>

Hi,

The patchset tries to fix the hard-up problem found when checking how htab
handles element reuse in bpf memory allocator. The immediate reuse of
freed elements will reinitialize special fields (e.g., bpf_spin_lock) in
htab map value and it may corrupt lookup procedure with BFP_F_LOCK flag
which acquires bpf-spin-lock during value copying, and lead to hard-lock
as shown in patch #2. Patch #1 fixes it by using __GFP_ZERO when allocating
the object from slab and the behavior is similar with the preallocated
hash-table case. Please see individual patches for more details. And comments
are always welcome.

Regards,

Change Log:
v1:
  * Use __GFP_ZERO instead of ctor to avoid retpoline overhead (from Alexei)
  * Add comments for check_and_init_map_value() (from Alexei)
  * split __GFP_ZERO patches out of the original patchset to unblock
    the development work of others.

RFC: https://lore.kernel.org/bpf/20221230041151.1231169-1-houtao@huaweicloud.com
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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3538a0fbbd81bc131afe48b4cf02895735944359