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charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: C89B514000C X-Stat-Signature: a7p6rnq1fujuhgo96n3fepmr77a1sfcq X-Rspam-User: X-HE-Tag: 1686743654-316242 X-HE-Meta: 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 OGuthS+8 4PHyAt2Py+VbgBJSKI1oWSRlK4d0YZno3c38eA6Vv4DovdJpq2NZwaZqChu2dEVkOlWX2dAPJmvQJ6LEXmX0fruCGsMw5GrXjCH8qm/hC22BrN3G9W/xsowI4agjiO642NazlJLETvhEGIJrGM+eKU1WpQxppGg9SQyQn6R28qVXSl30fOorsiwftqNt3+Z0u/71i1gn5utk9moe0BrvzOq0IUoDZ/cKdOqtBqEgERc0A8DpTBKY7b/M0+aZJW8cQc3JOLHpna8R1wG1PiErHNXxdE0YGNZL2HoMclXMAUbgNyrZTL/So9G5ut2tH/GjlGLiosNp6IOJqTxttc/VJ90CI1hoT7YZbrLX1oy/az8pGnNEoC+bzWNDbsRC3a6ZDqfNgFxHbdPW+P+DvjIlKQGkesKj8Ezk8k99pqJVSHeiqHsmQSI5vJ9czlg== 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: Hi, On Wed, Jun 14, 2023 at 11:28:32AM +0000, Yajun Deng wrote: > June 14, 2023 7:09 PM, "Greg KH" wrote: > > > On Wed, Jun 14, 2023 at 07:03:24PM +0800, Yajun Deng wrote: > > > >> When the system boots, only one cpu is enabled before smp_init(). > >> So the spinlock is not needed in most cases, remove it. > >> > >> Add spinlock in get_nid_for_pfn() because it is after smp_init(). > > > > So this is two different things at once in the same patch? > > > > Or are they the same problem and both need to go in to solve it? > > > > And if a spinlock is not needed at early boot, is it really causing any > > problems? > > > > They are the same problem. > I added pr_info in early_pfn_to_nid(), found get_nid_for_pfn() is the only > case need to add spinlock. > This patch tested on my x86 system. Are you sure it'll work on !x86? > >> Signed-off-by: Yajun Deng > >> --- > >> drivers/base/node.c | 11 +++++++++-- > >> mm/mm_init.c | 18 +++--------------- > >> 2 files changed, 12 insertions(+), 17 deletions(-) > >> > >> diff --git a/drivers/base/node.c b/drivers/base/node.c > >> index 9de524e56307..844102570ff2 100644 > >> --- a/drivers/base/node.c > >> +++ b/drivers/base/node.c > >> @@ -748,8 +748,15 @@ int unregister_cpu_under_node(unsigned int cpu, unsigned int nid) > >> static int __ref get_nid_for_pfn(unsigned long pfn) > >> { > >> #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT > >> - if (system_state < SYSTEM_RUNNING) > >> - return early_pfn_to_nid(pfn); > >> + static DEFINE_SPINLOCK(early_pfn_lock); > >> + int nid; > >> + > >> + if (system_state < SYSTEM_RUNNING) { > >> + spin_lock(&early_pfn_lock); > >> + nid = early_pfn_to_nid(pfn); > >> + spin_unlock(&early_pfn_lock); > > > > Adding an external lock for when you call a function is VERY dangerous > > as you did not document this anywhere, and there's no way to enforce it > > properly at all. > > > > I should add a comment before early_pfn_to_nid(). > > > Does your change actually result in any boot time changes? How was this > > tested? > > > > Just a bit. Just a bit tested? Or just a bit of boot time changes? For the latter, do you have numbers? -- Sincerely yours, Mike.