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Tue, 14 Jan 2020 20:20:11 +0000 (UTC) Received: from [10.36.118.60] (unknown [10.36.118.60]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4397E10372C0; Tue, 14 Jan 2020 20:20:09 +0000 (UTC) Subject: Re: [PATCH -next] mm/hotplug: silence a lockdep splat with printk() To: Qian Cai , akpm@linux-foundation.org Cc: mhocko@kernel.org, sergey.senozhatsky.work@gmail.com, pmladek@suse.com, rostedt@goodmis.org, peterz@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20200114201114.14696-1-cai@lca.pw> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: <6d9d2923-a44c-60fb-5caa-e6228cb8aaf5@redhat.com> Date: Tue, 14 Jan 2020 21:20:08 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 In-Reply-To: <20200114201114.14696-1-cai@lca.pw> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 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 14.01.20 21:11, Qian Cai wrote: > Similar to the recent commit [1] merged into the random and -next trees, > it is not a good idea to call printk() with zone->lock held. The > standard fix is to use printk_deferred() in those places, but memory > offline will call dump_page() which need to defer after the lock. While > at it, remove a similar but unnecessary debug printk() as well. > > [1] https://lore.kernel.org/lkml/1573679785-21068-1-git-send-email-cai@lca.pw/ > > Signed-off-by: Qian Cai > --- > include/linux/page-isolation.h | 2 +- > mm/memory_hotplug.c | 2 +- > mm/page_alloc.c | 12 +++++------- > mm/page_isolation.c | 10 +++++++++- > 4 files changed, 16 insertions(+), 10 deletions(-) > > diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h > index 148e65a9c606..5d8ba078006f 100644 > --- a/include/linux/page-isolation.h > +++ b/include/linux/page-isolation.h > @@ -34,7 +34,7 @@ static inline bool is_migrate_isolate(int migratetype) > #define REPORT_FAILURE 0x2 > > bool has_unmovable_pages(struct zone *zone, struct page *page, int migratetype, > - int flags); > + int flags, char *dump); > void set_pageblock_migratetype(struct page *page, int migratetype); > int move_freepages_block(struct zone *zone, struct page *page, > int migratetype, int *num_movable); > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 7a6de9b0dcab..f10928538fa3 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1149,7 +1149,7 @@ static bool is_pageblock_removable_nolock(unsigned long pfn) > return false; > > return !has_unmovable_pages(zone, page, MIGRATE_MOVABLE, > - MEMORY_OFFLINE); > + MEMORY_OFFLINE, NULL); > } > > /* Checks if this range of memory is likely to be hot-removable. */ > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index e56cd1f33242..b6bec3925e80 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -8204,7 +8204,7 @@ void *__init alloc_large_system_hash(const char *tablename, > * race condition. So you can't expect this function should be exact. > */ > bool has_unmovable_pages(struct zone *zone, struct page *page, int migratetype, > - int flags) > + int flags, char *dump) > { > unsigned long iter = 0; > unsigned long pfn = page_to_pfn(page); > @@ -8305,8 +8305,10 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int migratetype, > return false; > unmovable: > WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE); > - if (flags & REPORT_FAILURE) > - dump_page(pfn_to_page(pfn + iter), reason); > + if (flags & REPORT_FAILURE) { > + page = pfn_to_page(pfn + iter); > + strscpy(dump, reason, 64); > + } > return true; > } > > @@ -8711,10 +8713,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) > BUG_ON(!PageBuddy(page)); > order = page_order(page); > offlined_pages += 1 << order; > -#ifdef CONFIG_DEBUG_VM > - pr_info("remove from free list %lx %d %lx\n", > - pfn, 1 << order, end_pfn); > -#endif ack to getting rid of this. Regarding the other stuff, I remember Michal had an opinion about the previous approach, so it's best if he comments. -- Thanks, David / dhildenb