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From: Chengming Zhou In-Reply-To: <20250306230015.1456794-1-nphamcs@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1E2B5140006 X-Rspam-User: X-Stat-Signature: jwh5hazg55dyqkfom7cgem35b74zwdyj X-HE-Tag: 1741316937-353621 X-HE-Meta: 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 ZvSzW8bx YNOrtWaapWJMOjE2GYN3UVxZX3aRRna+7ABY562qYEEVMofmQpRFc+dHQJTMBI79SwPUWn5pql/5YWzYTWAQ5PtIGA4BzSrUOmHT2z0a8P2iTywQk4P/nHVWNr4QUuHMjKZ/mnY83PHI1vJ1zMH7hdbe1afIyQC0mYUtahZCKqearKy+A44LKWZmbBaaANTEgjxKgNzY4k+sJ701KaSGtCNrx3T8sq0shCjoH5ADahJHQRmPySp119MBvfJqXA4ZymHVEaQsam8/f1rAvcWhLt2tjBwzqg3RYaM7BS97SFgNU3GVkBLatkTzHgIxoPiEvYa9h+AORyOSKxBjgSOOm7N2DOg== 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: List-Subscribe: List-Unsubscribe: On 2025/3/7 07:00, Nhat Pham wrote: > Similar to zswap_load(), also return proper error codes for > swap_read_folio_zeromap(): > > * 0 on success. The folio is unlocked and marked up-to-date. > * -ENOENT, if the folio is entirely not zeromapped. > * -EINVAL (with the follio unlocked but not marked to date), if the > folio is partially zeromapped. This is not supported, and will SIGBUS > the faulting process. > > This patch is purely a clean-up, and should not have any behavioral > change. It is based on (and should be applied on top of) [1]. > > [1]: https://lore.kernel.org/linux-mm/20250306205011.784787-1-nphamcs@gmail.com/ > > Suggested-by: Yosry Ahmed > Suggested-by: Johannes Weiner > Signed-off-by: Nhat Pham Reviewed-by: Chengming Zhou Thanks! > --- > mm/page_io.c | 35 ++++++++++++++++++++++++++--------- > 1 file changed, 26 insertions(+), 9 deletions(-) > > diff --git a/mm/page_io.c b/mm/page_io.c > index 4bce19df557b..48ed1e810392 100644 > --- a/mm/page_io.c > +++ b/mm/page_io.c > @@ -511,7 +511,23 @@ static void sio_read_complete(struct kiocb *iocb, long ret) > mempool_free(sio, sio_pool); > } > > -static bool swap_read_folio_zeromap(struct folio *folio) > +/** > + * swap_read_folio_zeromap - check if the folio was zeromapped, and if so, > + * zero-fill it. > + * @folio: the folio. > + * > + * Return: 0 on success, with the folio zero-filled, unlocked, and marked > + * up-to-date, or one of the following error codes: > + * > + * -ENOENT: the folio is entirely not zeromapped. The folio remains locked. > + * > + * -EINVAL: some of the subpages in the folio are zeromaped, but not all of > + * them. This is an error because we don't currently support a large folio > + * that is partially in the zeromap. The folio is unlocked, but NOT marked > + * up-to-date, so that an IO error is emitted (e.g. do_swap_page() will > + * sigbus). > + */ > +static int swap_read_folio_zeromap(struct folio *folio) > { > int nr_pages = folio_nr_pages(folio); > struct obj_cgroup *objcg; > @@ -519,15 +535,17 @@ static bool swap_read_folio_zeromap(struct folio *folio) > > /* > * Swapping in a large folio that is partially in the zeromap is not > - * currently handled. Return true without marking the folio uptodate so > + * currently handled. Return -EINVAL without marking the folio uptodate so > * that an IO error is emitted (e.g. do_swap_page() will sigbus). > */ > if (WARN_ON_ONCE(swap_zeromap_batch(folio->swap, nr_pages, > - &is_zeromap) != nr_pages)) > - return true; > + &is_zeromap) != nr_pages)) { > + folio_unlock(folio); > + return -EINVAL; > + } > > if (!is_zeromap) > - return false; > + return -ENOENT; > > objcg = get_obj_cgroup_from_folio(folio); > count_vm_events(SWPIN_ZERO, nr_pages); > @@ -538,7 +556,8 @@ static bool swap_read_folio_zeromap(struct folio *folio) > > folio_zero_range(folio, 0, folio_size(folio)); > folio_mark_uptodate(folio); > - return true; > + folio_unlock(folio); > + return 0; > } > > static void swap_read_folio_fs(struct folio *folio, struct swap_iocb **plug) > @@ -635,10 +654,8 @@ void swap_read_folio(struct folio *folio, struct swap_iocb **plug) > } > delayacct_swapin_start(); > > - if (swap_read_folio_zeromap(folio)) { > - folio_unlock(folio); > + if (swap_read_folio_zeromap(folio) != -ENOENT) > goto finish; > - } > > if (zswap_load(folio) != -ENOENT) > goto finish;