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charset=us-ascii Content-Disposition: inline In-Reply-To: <20230615073226.1343-2-haifeng.xu@shopee.com> X-Rspamd-Queue-Id: 110D8C0016 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: qco9q9q54fiwxwytpdmfucj8rdyuu6oy X-HE-Tag: 1686817583-248239 X-HE-Meta: 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 Rr8eT+Mo 6GFx3e/XRaCDlShTfAWM5R7lP/wJ64FZmJO9ZsfCMr8ArJfofzNvf3nNCBxSRihnV539IjFBdVfmz2DTmnKqdHCLcOwVz2/3sJ88pg0vZAlpR2dk5sUlwYH/fK1so2PjvA5Ujpz50rJwYGI9BWGEvGgN0SptdkbR6Jsyk2/FNpdEHz898RE3lNEbjbRzVyYnpy8u2FHPyoIOGl/EYkLKidc9MzCemEvtfM7B52Sx/Sz5UOQ77QdmD15YRocQrd8Z8wJZ4 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu 15-06-23 07:32:26, Haifeng Xu wrote: > If mem_cgroup_init() fails to allocate mem_cgroup_tree_per_node, we > should not try to initilaize it. Add check for this case to avoid > potential NULL pointer dereference. Technically yes and it seems that all users of soft_limit_tree.rb_tree_per_node correctly check for NULL so this would be graceful failure handling. At least superficially because the feature itself would be semi-broken when used. But more practically this is a 24B allocation and if we fail to allocate that early during the boot we are screwed anyway. Would such a system have any chance to boot all the way to userspace? Woul any userspace actually work? Is this patch motivated by a code reading or is there any actual practical upside of handling the error here? > Signed-off-by: Haifeng Xu > --- > mm/memcontrol.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index c73c5fb33f65..7ebf64e48b25 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -7422,6 +7422,8 @@ static int __init mem_cgroup_init(void) > struct mem_cgroup_tree_per_node *rtpn; > > rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, node); > + if (!rtpn) > + continue; > > rtpn->rb_root = RB_ROOT; > rtpn->rb_rightmost = NULL; > -- > 2.25.1 -- Michal Hocko SUSE Labs