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Miller" , Jakub Kicinski , Paolo Abeni , Andrew Morton , willy@infradead.org Date: Tue, 25 Apr 2023 19:15:48 +0200 Message-ID: <168244294889.1741095.16231421250476473539.stgit@firesoul> In-Reply-To: <168244288038.1741095.1092368365531131826.stgit@firesoul> References: <168244288038.1741095.1092368365531131826.stgit@firesoul> User-Agent: StGit/1.4 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 X-Stat-Signature: e47gdyjnrog6ybeatbmmskbcz1t899r5 X-Rspam-User: X-Rspamd-Queue-Id: BFE97A000F X-Rspamd-Server: rspam06 X-HE-Tag: 1682442954-284774 X-HE-Meta: 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 aZPUwysY LY5lcXOYwkeFDGRTQHCLmqhzGvEVC5x9RFKissbo6L7EsagC1pYdRzJTm0cW/sDGgJ8iaHAvkMf06sAR9lTix8HzpMlylOEdqUaYUu3lT82hL9tNdAvbCGFqzt0uDdozv/NPPHQflZCQWfY5RSsKaSihU7KE3dcD7+vHescmDZA4rR6H++eLEcKtELkzRx+qSFh3OD1BVyGDt5qVoyNImX54kNmXkwiY0Igdft9HtBg8/L1ytsvE5VV++t/BqtKdRGYNVxmicoh43OSgOUk23dPt7m1TofBCr8I16MegMm8O6NMt8avVHB4BHSTnt0NcmUZDL 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: Pages belonging to a page_pool (PP) instance must be freed through the PP APIs in-order to correctly release any DMA mappings and release refcnt on the DMA device when freeing PP instance. When PP release a page (page_pool_release_page) the page->pp_magic value is cleared. This patch detect a leaked PP page in free_page_is_bad() via unexpected state of page->pp_magic value being PP_SIGNATURE. We choose to report and treat it as a bad page. It would be possible to release the page via returning it to the PP instance as the page->pp pointer is likely still valid. Notice this code is only activated when either compiled with CONFIG_DEBUG_VM or boot cmdline debug_pagealloc=on, and CONFIG_PAGE_POOL. Reduced example output of leak with PP_SIGNATURE = dead000000000040: BUG: Bad page state in process swapper/0 pfn:110bbf page:000000005bc8cfb8 refcount:0 mapcount:0 mapping:0000000000000000 index:0x110bbf000 pfn:0x110bbf flags: 0x2fffff80000000(node=0|zone=2|lastcpupid=0x1fffff) raw: 002fffff80000000 dead000000000040 ffff888117255000 0000000000000000 raw: 0000000110bbf000 000000000000003e 00000000ffffffff 0000000000000000 page dumped because: page_pool leak [...] Signed-off-by: Jesper Dangaard Brouer --- mm/page_alloc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 8e39705c7bdc..137b72f8ab8b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1247,6 +1247,9 @@ static inline bool page_expected_state(struct page *page, page_ref_count(page) | #ifdef CONFIG_MEMCG page->memcg_data | +#endif +#ifdef CONFIG_PAGE_POOL + ((page->pp_magic & ~0x3UL) == PP_SIGNATURE) | #endif (page->flags & check_flags))) return false; @@ -1273,6 +1276,10 @@ static const char *page_bad_reason(struct page *page, unsigned long flags) #ifdef CONFIG_MEMCG if (unlikely(page->memcg_data)) bad_reason = "page still charged to cgroup"; +#endif +#ifdef CONFIG_PAGE_POOL + if (unlikely((page->pp_magic & ~0x3UL) == PP_SIGNATURE)) + bad_reason = "page_pool leak"; #endif return bad_reason; }