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charset="UTF-8" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 581EB1C0009 X-Stat-Signature: oprtkpzzncwap9bzqmddo8u8xzw5iwe8 X-Spamd-Result: default: False [7.35 / 9.00]; TC_DBL_BL_100(5.00)[163.com:email]; SORBS_IRL_BL(3.00)[209.85.217.43:from]; BAYES_HAM(-0.75)[77.13%]; MIME_GOOD(-0.10)[text/plain]; BAD_REP_POLICIES(0.10)[]; RCVD_NO_TLS_LAST(0.10)[]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; DKIM_TRACE(0.00)[google.com:+]; DMARC_POLICY_ALLOW(0.00)[google.com,reject]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; PREVIOUSLY_DELIVERED(0.00)[linux-mm@kvack.org]; R_DKIM_ALLOW(0.00)[google.com:s=20210112]; ARC_SIGNED(0.00)[hostedemail.com:s=arc-20220608:i=1]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(0.00)[+ip4:209.85.128.0/17]; TO_DN_SOME(0.00)[]; ARC_NA(0.00)[] X-Rspam-User: X-HE-Tag: 1670039092-517608 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 Fri, Dec 2, 2022 at 12:00 PM Andrew Morton wrote: > > On Fri, 2 Dec 2022 22:16:30 +0800 tzm wrote: > > > It will be failed to disable numa balancing policy permanently by passing > > to boot cmdline parameters. > > The numabalancing_override variable is int and 1 for enable -1 for disable. > > So, !enumabalancing_override will always be true, which cause this bug. > > That's really old code! > > > --- a/mm/mempolicy.c > > +++ b/mm/mempolicy.c > > @@ -2865,7 +2865,7 @@ static void __init check_numabalancing_enable(void) > > if (numabalancing_override) > > set_numabalancing_state(numabalancing_override == 1); > > > > - if (num_online_nodes() > 1 && !numabalancing_override) { > > + if (num_online_nodes() > 1 && (numabalancing_override == 1)) { > > pr_info("%s automatic NUMA balancing. Configure with numa_balancing= or the kernel.numa_balancing sysctl\n", > > numabalancing_default ? "Enabling" : "Disabling"); > > set_numabalancing_state(numabalancing_default); > > Looks right to me. Mel? > Maybe I'm missing something, but it looks wrong to me? numabalancing_override is default initialized to 0, I think, indicating that no override exists. numabalancing_override == 1 indicates it has been overridden to true. numabalancing_override == -1 indicates that it has been overridden to false. The above code reads to me: if (override_exists) set_numabalancing_state(override_value) if (num_online_nodes() > ! && !override_exists) set_numabalancing_state(numabalancing_default) A more clear fix for readability would be an early return between these 2 if statements I think. > After eight years, I wonder if we actually need this. >