From patchwork Wed Dec 27 07:38:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Kasireddy, Vivek" X-Patchwork-Id: 13505185 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 406F0C46CD2 for ; Wed, 27 Dec 2023 08:02:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5BF0A8D0009; Wed, 27 Dec 2023 03:02:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 547A88D0001; Wed, 27 Dec 2023 03:02:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 374EB8D0009; Wed, 27 Dec 2023 03:02:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 198DC8D0001 for ; Wed, 27 Dec 2023 03:02:46 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id E45531606C3 for ; Wed, 27 Dec 2023 08:02:45 +0000 (UTC) X-FDA: 81611856690.12.4E0D88C Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.43]) by imf20.hostedemail.com (Postfix) with ESMTP id CDEDA1C000F for ; Wed, 27 Dec 2023 08:02:43 +0000 (UTC) Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=PRJCulGW; spf=pass (imf20.hostedemail.com: domain of vivek.kasireddy@intel.com designates 192.55.52.43 as permitted sender) smtp.mailfrom=vivek.kasireddy@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1703664164; a=rsa-sha256; cv=none; b=I5uWBU5I0Kvz637Q4Rtj81WbJYu8Dhja7OZ3XFOIQUq2/r4/Fa5xrGntgMQLkK7gRlfeJT IrE5Z3f7FC3pP1f06HEyDSUJFpjgLY9MEk3jEbqTIpqhnlljN5yvivoaFkxz1A0G8UPuFn 6I58G/fSxeun1uYBXH1ANh90u6Dt1s4= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=PRJCulGW; spf=pass (imf20.hostedemail.com: domain of vivek.kasireddy@intel.com designates 192.55.52.43 as permitted sender) smtp.mailfrom=vivek.kasireddy@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1703664164; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Y329FJ3UdvBikNiGvIBNgIzWPQ8UL0tCZzkHiz1VAuY=; b=pPccA3m3Nj//iJlPLHlOmmyId0vHPrRNeydJzbUCxprENirdm4WjUtOj2VDFDKPfyUFFkk fhNdXW6qOhW2kfzzE1teOsGWV+545Wop+kaRZFjmZKBvh3GV4zXVRFfChoO7HCz+FLm5Tw kALnMcwQSoOA8LAzpQUgXCRyERWCpC8= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1703664163; x=1735200163; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Ysvgkra0A4hz+Fh+hWsAQrFZ6yvogefwsiMZ4geO3JM=; b=PRJCulGWJFmATD4aolaGk6qK5lZn9FCnhsNaJZ3BuogNV37Jdx3EzWfL x5LQx7i4R+F5U4NQ9ywIybpZyAyqogbncUPSbDI8fiaeX/XT8FJPLrsMF YEtG6LFp4JMX0kDIy9JqWr8h+2JeYMUgAUbM0/420XtHVut+cf6eJrOJr b9/g5ZyhNpQy+diRgHsKxnlnFl25NOZEmOuWH4hd4oIdwVD07k8Gz4sLb CmiTITCqJSZGeKhk9qk0D5ta6QmpkMDefpfdew1/1x06l3/1mjD5eScA2 5T0sx/SnMgmbseEGJv/h7FjFymPb644Tm6h8wXHkOwebdy+lmrf9XAasN A==; X-IronPort-AV: E=McAfee;i="6600,9927,10935"; a="482604304" X-IronPort-AV: E=Sophos;i="6.04,308,1695711600"; d="scan'208";a="482604304" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Dec 2023 00:02:36 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10935"; a="781668188" X-IronPort-AV: E=Sophos;i="6.04,308,1695711600"; d="scan'208";a="781668188" Received: from vkasired-desk2.fm.intel.com ([10.105.128.132]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Dec 2023 00:02:36 -0800 From: Vivek Kasireddy To: dri-devel@lists.freedesktop.org, linux-mm@kvack.org Cc: Vivek Kasireddy , David Hildenbrand , Matthew Wilcox , Christoph Hellwig , Daniel Vetter , Mike Kravetz , Hugh Dickins , Peter Xu , Gerd Hoffmann , Dongwon Kim , Junxiao Chang , Jason Gunthorpe , Christoph Hellwig Subject: [PATCH v9 3/6] mm/gup: Introduce memfd_pin_folios() for pinning memfd folios (v9) Date: Tue, 26 Dec 2023 23:38:19 -0800 Message-Id: <20231227073822.390518-4-vivek.kasireddy@intel.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20231227073822.390518-1-vivek.kasireddy@intel.com> References: <20231227073822.390518-1-vivek.kasireddy@intel.com> MIME-Version: 1.0 X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: CDEDA1C000F X-Stat-Signature: ua9566qsym4q1fuc4w8pekffiheec8zo X-Rspam-User: X-HE-Tag: 1703664163-983722 X-HE-Meta: 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 6EhgYjyz GaMVQSZ7C8Q2BtVp1lNNCCMDGGEd80a1j3CW2lWSmH0HNRdIA4jrVBE+ZvmqTyoV/bZN3LOSgH3h4c46Q9eATeSPG0w56+c85SPXf2RRUFbjS6gxzdIf07uVnWI7zT0L/FV46HlUHXLNOPdDZpOkJhg+1AZ0HcvJHPNvyhaLlIbf83uq/qLV6FtUQ7OodSHRuGxhVMhxMSW7cfotP4d+P9Uk8+JIjnPdtw/rO2UzfY81g/esdqVUqjAtnmu0whAhwsempRpZKGxWzqUNEuINBMSK318DcJlBO+R9ZQvtJRzI5cbxmOBpTtZys8/l0pfLkcHg16HR0dlsc5GfaZcJOx+Cxh62gldZ3h/kOllMiBh9Qxnk= 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: For drivers that would like to longterm-pin the folios associated with a memfd, the memfd_pin_folios() API provides an option to not only pin the folios via FOLL_PIN but also to check and migrate them if they reside in movable zone or CMA block. This API currently works with memfds but it should work with any files that belong to either shmemfs or hugetlbfs. Files belonging to other filesystems are rejected for now. The folios need to be located first before pinning them via FOLL_PIN. If they are found in the page cache, they can be immediately pinned. Otherwise, they need to be allocated using the filesystem specific APIs and then pinned. v2: - Drop gup_flags and improve comments and commit message (David) - Allocate a page if we cannot find in page cache for the hugetlbfs case as well (David) - Don't unpin pages if there is a migration related failure (David) - Drop the unnecessary nr_pages <= 0 check (Jason) - Have the caller of the API pass in file * instead of fd (Jason) v3: (David) - Enclose the huge page allocation code with #ifdef CONFIG_HUGETLB_PAGE (Build error reported by kernel test robot ) - Don't forget memalloc_pin_restore() on non-migration related errors - Improve the readability of the cleanup code associated with non-migration related errors - Augment the comments by describing FOLL_LONGTERM like behavior - Include the R-b tag from Jason v4: - Remove the local variable "page" and instead use 3 return statements in alloc_file_page() (David) - Add the R-b tag from David v5: (David) - For hugetlb case, ensure that we only obtain head pages from the mapping by using __filemap_get_folio() instead of find_get_page_flags() - Handle -EEXIST when two or more potential users try to simultaneously add a huge page to the mapping by forcing them to retry on failure v6: (Christoph) - Rename this API to memfd_pin_user_pages() to make it clear that it is intended for memfds - Move the memfd page allocation helper from gup.c to memfd.c - Fix indentation errors in memfd_pin_user_pages() - For contiguous ranges of folios, use a helper such as filemap_get_folios_contig() to lookup the page cache in batches v7: - Rename this API to memfd_pin_folios() and make it return folios and offsets instead of pages (David) - Don't continue processing the folios in the batch returned by filemap_get_folios_contig() if they do not have correct next_idx - Add the R-b tag from Christoph v8: (David) - Have caller pass [start, end], max_folios instead of start, nr_pages - Replace offsets array with just offset into the first page - Add comments explaning the need for next_idx - Pin (and return) the folio (via FOLL_PIN) only once v9: (Matthew) - Drop the extern while declaring memfd_alloc_folio() - Fix memfd_alloc_folio() declaration to have it return struct folio * instead of struct page * when CONFIG_MEMFD_CREATE is not defined Cc: David Hildenbrand Cc: Matthew Wilcox (Oracle) Cc: Christoph Hellwig Cc: Daniel Vetter Cc: Mike Kravetz Cc: Hugh Dickins Cc: Peter Xu Cc: Gerd Hoffmann Cc: Dongwon Kim Cc: Junxiao Chang Suggested-by: Jason Gunthorpe Reviewed-by: Jason Gunthorpe (v2) Reviewed-by: David Hildenbrand (v3) Reviewed-by: Christoph Hellwig (v6) Signed-off-by: Vivek Kasireddy --- include/linux/memfd.h | 5 ++ include/linux/mm.h | 3 + mm/gup.c | 149 ++++++++++++++++++++++++++++++++++++++++++ mm/memfd.c | 34 ++++++++++ 4 files changed, 191 insertions(+) diff --git a/include/linux/memfd.h b/include/linux/memfd.h index e7abf6fa4c52..3f2cf339ceaf 100644 --- a/include/linux/memfd.h +++ b/include/linux/memfd.h @@ -6,11 +6,16 @@ #ifdef CONFIG_MEMFD_CREATE extern long memfd_fcntl(struct file *file, unsigned int cmd, unsigned int arg); +struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx); #else static inline long memfd_fcntl(struct file *f, unsigned int c, unsigned int a) { return -EINVAL; } +static inline struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx) +{ + return ERR_PTR(-EINVAL); +} #endif #endif /* __LINUX_MEMFD_H */ diff --git a/include/linux/mm.h b/include/linux/mm.h index 418d26608ece..942d2e618253 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2472,6 +2472,9 @@ long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, struct page **pages, unsigned int gup_flags); long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages, struct page **pages, unsigned int gup_flags); +long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end, + struct folio **folios, unsigned int max_folios, + pgoff_t *offset); int get_user_pages_fast(unsigned long start, int nr_pages, unsigned int gup_flags, struct page **pages); diff --git a/mm/gup.c b/mm/gup.c index 231711efa390..42eb212af73f 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -5,6 +5,7 @@ #include #include +#include #include #include #include @@ -17,6 +18,7 @@ #include #include #include +#include #include #include @@ -3410,3 +3412,150 @@ long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages, &locked, gup_flags); } EXPORT_SYMBOL(pin_user_pages_unlocked); + +/** + * memfd_pin_folios() - pin folios associated with a memfd + * @memfd: the memfd whose folios are to be pinned + * @start: the first memfd offset + * @end: the last memfd offset (inclusive) + * @folios: array that receives pointers to the folios pinned + * @max_folios: maximum number of entries in @folios + * @offset: the offset into the first folio + * + * Attempt to pin folios associated with a memfd in the contiguous range + * [start, end]. Given that a memfd is either backed by shmem or hugetlb, + * the folios can either be found in the page cache or need to be allocated + * if necessary. Once the folios are located, they are all pinned via + * FOLL_PIN and @offset is populatedwith the offset into the first folio. + * And, eventually, these pinned folios must be released either using + * unpin_user_pages() or unpin_user_page(). + * + * It must be noted that the folios may be pinned for an indefinite amount + * of time. And, in most cases, the duration of time they may stay pinned + * would be controlled by the userspace. This behavior is effectively the + * same as using FOLL_LONGTERM with other GUP APIs. + * + * Returns number of folios pinned, which could be less than @max_folios + * as it depends on the folio sizes that cover the range [start, end]. + * If no folios were pinned, it returns -errno. + */ +long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end, + struct folio **folios, unsigned int max_folios, + pgoff_t *offset) +{ + unsigned int flags, nr_folios, nr_found; + unsigned int i, pgshift = PAGE_SHIFT; + pgoff_t start_idx, end_idx, next_idx; + struct folio *folio = NULL; + struct folio_batch fbatch; + struct page **pages; + struct hstate *h; + long ret; + + if (start > end || !max_folios) + return -EINVAL; + + if (!memfd) + return -EINVAL; + + if (!shmem_file(memfd) && !is_file_hugepages(memfd)) + return -EINVAL; + + pages = kmalloc_array(max_folios, sizeof(*pages), GFP_KERNEL); + if (!pages) + return -ENOMEM; + + if (is_file_hugepages(memfd)) { + h = hstate_file(memfd); + pgshift = huge_page_shift(h); + } + + flags = memalloc_pin_save(); + do { + nr_folios = 0; + start_idx = start >> pgshift; + end_idx = end >> pgshift; + if (is_file_hugepages(memfd)) { + start_idx <<= huge_page_order(h); + end_idx <<= huge_page_order(h); + } + + folio_batch_init(&fbatch); + while (start_idx <= end_idx && nr_folios < max_folios) { + /* + * In most cases, we should be able to find the folios + * in the page cache. If we cannot find them for some + * reason, we try to allocate them and add them to the + * page cache. + */ + nr_found = filemap_get_folios_contig(memfd->f_mapping, + &start_idx, + end_idx, + &fbatch); + if (folio) { + folio_put(folio); + folio = NULL; + } + + next_idx = 0; + for (i = 0; i < nr_found; i++) { + /* + * As there can be multiple entries for a + * given folio in the batch returned by + * filemap_get_folios_contig(), the below + * check is to ensure that we pin and return a + * unique set of folios between start and end. + */ + if (next_idx && + next_idx != folio_index(fbatch.folios[i])) + continue; + + folio = try_grab_folio(&fbatch.folios[i]->page, + 1, FOLL_PIN); + if (!folio) { + folio_batch_release(&fbatch); + kfree(pages); + goto err; + } + + if (nr_folios == 0) + *offset = offset_in_folio(folio, start); + + folios[nr_folios] = folio; + pages[nr_folios] = folio_page(folio, 0); + next_idx = folio_next_index(folio); + + if (++nr_folios == max_folios) + break; + } + + folio = NULL; + folio_batch_release(&fbatch); + if (!nr_found) { + folio = memfd_alloc_folio(memfd, start_idx); + if (IS_ERR(folio)) { + ret = PTR_ERR(folio); + if (ret != -EEXIST) { + kfree(pages); + goto err; + } + } + } + } + + ret = check_and_migrate_movable_pages(nr_folios, pages); + } while (ret == -EAGAIN); + + kfree(pages); + memalloc_pin_restore(flags); + return ret ? ret : nr_folios; +err: + memalloc_pin_restore(flags); + while (i-- > 0) + if (folios[i]) + gup_put_folio(folios[i], 1, FOLL_PIN); + + return ret; +} +EXPORT_SYMBOL_GPL(memfd_pin_folios); + diff --git a/mm/memfd.c b/mm/memfd.c index d3a1ba4208c9..36a75e8249f8 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -63,6 +63,40 @@ static void memfd_tag_pins(struct xa_state *xas) xas_unlock_irq(xas); } +/* + * This is a helper function used by memfd_pin_user_pages() in GUP (gup.c). + * It is mainly called to allocate a page in a memfd when the caller + * (memfd_pin_user_pages()) cannot find a page in the page cache at a given + * index in the mapping. + */ +struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx) +{ +#ifdef CONFIG_HUGETLB_PAGE + struct folio *folio; + int err; + + if (is_file_hugepages(memfd)) { + folio = alloc_hugetlb_folio_nodemask(hstate_file(memfd), + NUMA_NO_NODE, + NULL, + GFP_USER); + if (folio && folio_try_get(folio)) { + err = hugetlb_add_to_page_cache(folio, + memfd->f_mapping, + idx); + if (err) { + folio_put(folio); + free_huge_folio(folio); + return ERR_PTR(err); + } + return folio; + } + return ERR_PTR(-ENOMEM); + } +#endif + return shmem_read_folio(memfd->f_mapping, idx); +} + /* * Setting SEAL_WRITE requires us to verify there's no pending writer. However, * via get_user_pages(), drivers might have some pending I/O without any active