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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qic8y-000DqW-3x; Tue, 19 Sep 2023 14:56:04 +0000 Date: Tue, 19 Sep 2023 15:56:04 +0100 From: Matthew Wilcox To: Daniel Gomez Cc: "minchan@kernel.org" , "senozhatsky@chromium.org" , "axboe@kernel.dk" , "djwong@kernel.org" , "hughd@google.com" , "akpm@linux-foundation.org" , "mcgrof@kernel.org" , "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "linux-xfs@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "gost.dev@samsung.com" , Pankaj Raghav Subject: Re: [PATCH v2 2/6] shmem: return freed pages in shmem_free_swap Message-ID: References: <20230919135536.2165715-1-da.gomez@samsung.com> <20230919135536.2165715-3-da.gomez@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230919135536.2165715-3-da.gomez@samsung.com> X-Rspam-User: X-Stat-Signature: y5st6urqdyfu4jwdztykg5xhw76rcgpd X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 1D91A40030 X-HE-Tag: 1695135373-9853 X-HE-Meta: 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 0laWGSZK e7r0HeJYu1gpbZanXjRy3Q2oZLea2yn8GksWWGXVw729Xlc0+BT5nnncDZG4CE0nfXTL9S22zGj1lh3pCE+vKVhNemljy81I/OKxZXSJhyjKgSrzdYkLQ9yuzY3Pcd1k3zz4CqanBiK2KDOipNE22BiCjtxcizWLTwxXsEnRvCBvZCx29GRR2naVSUR8KPjMrE00GvfqtdFjkgF5SdciXyFqQp5tntwdg51cy 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 Tue, Sep 19, 2023 at 01:55:47PM +0000, Daniel Gomez wrote: > +++ b/mm/shmem.c > @@ -846,16 +846,18 @@ static void shmem_delete_from_page_cache(struct folio *folio, void *radswap) > /* > * Remove swap entry from page cache, free the swap and its page cache. > */ > -static int shmem_free_swap(struct address_space *mapping, > +static long shmem_free_swap(struct address_space *mapping, > pgoff_t index, void *radswap) > { > void *old; > > old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0); > if (old != radswap) > - return -ENOENT; > + return 0; > + > free_swap_and_cache(radix_to_swp_entry(radswap)); > - return 0; > + > + return folio_nr_pages((struct folio *)radswap); > } Oh my goodness. I have led you astray; my apologies. shmem_free_swap() is called when the 'folio' is NOT actually a folio. It's an 'exceptional' / 'value' entry. We can't do this. Do we encode the size of the swap entry in the swp_entry_t or do we have to get that information from the XArray (which no longer knows it after we've stored a NULL there)?