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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1q8ijI-002jGU-FS; Mon, 12 Jun 2023 14:41:12 +0000 Date: Mon, 12 Jun 2023 15:41:12 +0100 From: Matthew Wilcox To: Kefeng Wang Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, jgowans@amazon.com, yuzhao@google.com Subject: Re: [PATCH -next 1/2] mm: compaction: convert to use a folio in isolate_migratepages_block() Message-ID: References: <20230612143414.186389-1-wangkefeng.wang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230612143414.186389-1-wangkefeng.wang@huawei.com> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: A68571C0023 X-Stat-Signature: nsop8cjd1hpigfoiwtj7im97xb88q9jw X-Rspam-User: X-HE-Tag: 1686580876-815476 X-HE-Meta: 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 O5JtjuL9 rmSU77uNNNsGSNVMlDLWt9PcMRAKsh3QtGiKjWIui1GNDJfbSxHxgQVzeHH3f0c4/79PWmrrSNl/0qFoOU/wRrQt8m/2P4OUUhobX4AUar82SLn6fV0metZrZCynHc+Wsxuvi9V+hz1baGjmLpg1Ck1zBvnzUJpYuQgHaqGaxQPmNVTY2U7geEPS3KQ== 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 Mon, Jun 12, 2023 at 10:34:13PM +0800, Kefeng Wang wrote: > @@ -959,7 +960,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, > * Hugepage was successfully isolated and placed > * on the cc->migratepages list. > */ > - low_pfn += compound_nr(page) - 1; > + folio = page_folio(page); > + low_pfn += folio_nr_pages(folio) - 1; > goto isolate_success_no_list; Why is this safe? That is, how do we know that the folio can't be dissolved under us at this point, then reallocated and hit the VM_BUG_ON_PGFLAGS(PageTail(page), page) in folio_flags() when we test folio_test_large()? > @@ -1132,30 +1137,30 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, > * and it's on LRU. It can only be a THP so the order > * is safe to read and it's 0 for tail pages. > */ ^^^ This comment needs to be updated too. > - mod_node_page_state(page_pgdat(page), > - NR_ISOLATED_ANON + page_is_file_lru(page), > - thp_nr_pages(page)); > + lruvec_del_folio(lruvec, folio); > + mod_node_page_state(folio_pgdat(folio), > + NR_ISOLATED_ANON + folio_is_file_lru(folio), > + folio_nr_pages(folio)); node_stat_mod_folio()