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Date:   Fri, 26 Aug 2022 12:49:25 +0200
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Subject: Re: [PATCH v4] page_ext: introduce boot parameter 'early_page_ext'
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To:     Andrew Morton <akpm@linux-foundation.org>, lizhe.67@bytedance.com
Cc:     mhocko@suse.com, mhiramat@kernel.org, keescook@chromium.org,
        Jason@zx2c4.com, mark-pk.tsai@mediatek.com, rostedt@goodmis.org,
        corbet@lwn.net, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        lizefan.x@bytedance.com
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 <20220825212338.e541d29ca3c4d602221f4925@linux-foundation.org>
From:   Vlastimil Babka <vbabka@suse.cz>
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On 8/26/22 06:23, Andrew Morton wrote:
> On Thu, 25 Aug 2022 18:27:14 +0800 lizhe.67@bytedance.com wrote:
> 
>> From: Li Zhe <lizhe.67@bytedance.com>
>> 
>> In 'commit 2f1ee0913ce5 ("Revert "mm: use early_pfn_to_nid in page_ext_init"")',
>> we call page_ext_init() after page_alloc_init_late() to avoid some panic
>> problem. It seems that we cannot track early page allocations in current
>> kernel even if page structure has been initialized early.
>> 
>> This patch introduce a new boot parameter 'early_page_ext' to resolve this
>> problem. If we pass it to kernel, function page_ext_init() will be moved
>> up and feature 'deferred initialization of struct pages' will be disabled
>> to initialize the page allocator early and prevent from the panic problem
>> above. It can help us to catch early page allocations. This is useful
>> especially when we find that the free memory value is not the same right
>> after different kernel booting.
>> 
> 
> WARNING: modpost: vmlinux.o: section mismatch in reference: early_page_ext_enabled (section: .text.unlikely) -> early_page_ext (section: .meminit.data)
> WARNING: modpost: vmlinux.o: section mismatch in reference: early_page_ext_enabled (section: .text.unlikely) -> early_page_ext (section: .meminit.data)

Hm it's a very small static inline, shouldn't exist separately anywhere.
Maybe it's due to that new debug info level thing?

Would this work instead?

----8<----
diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index 884282a7f03a..4bf4e58cf2d4 100644
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -40,7 +40,7 @@ extern bool early_page_ext;
 extern unsigned long page_ext_size;
 extern void pgdat_page_ext_init(struct pglist_data *pgdat);
 
-static inline bool early_page_ext_enabled(void)
+static inline bool __meminit early_page_ext_enabled(void)
 {
 	return early_page_ext;
 }