From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 153DEC07E9B for ; Fri, 9 Jul 2021 17:51:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 96BFE613CC for ; Fri, 9 Jul 2021 17:51:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 96BFE613CC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 438076B0074; Fri, 9 Jul 2021 13:51:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3E7306B0078; Fri, 9 Jul 2021 13:51:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 261F38D0001; Fri, 9 Jul 2021 13:51:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0204.hostedemail.com [216.40.44.204]) by kanga.kvack.org (Postfix) with ESMTP id E49C66B0074 for ; Fri, 9 Jul 2021 13:51:09 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 1D7F71649F for ; Fri, 9 Jul 2021 17:51:09 +0000 (UTC) X-FDA: 78343790658.15.75437D8 Received: from mail-pj1-f41.google.com (mail-pj1-f41.google.com [209.85.216.41]) by imf04.hostedemail.com (Postfix) with ESMTP id AC237500009F for ; Fri, 9 Jul 2021 17:51:08 +0000 (UTC) Received: by mail-pj1-f41.google.com with SMTP id p14-20020a17090ad30eb02901731c776526so6348042pju.4 for ; Fri, 09 Jul 2021 10:51:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=d/sMV2mqnVxpHb+Jh4Ox0/pgOOprIGWewt8+N7MTGsQ=; b=i7QnlekLD0vZWkUuFCZcPIP9sJZ+ecwaI1dmx06LLcmxlR2fCMiiK2FSSCPRWhgchq 8/UU7M3RqQvSLgqOBEIWePBiq/gzhVyswxor2ghWgr5DnVUzZTNexY7JLfObYoLr/7pH baLzQbRZlkt6FW1Tngtn1XtT79AZeLGz3A6VQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=d/sMV2mqnVxpHb+Jh4Ox0/pgOOprIGWewt8+N7MTGsQ=; b=MqN7yoefaQHkatoHX+cHtOXM/OyBRjYmE+OXam25AxSXSkrDuBEtvEffclkkiA3eH+ +/jG8fUe9dF5wmBluWJbOsWbKWjBTCLEQLm9FCLEuyAwwP9YbztQt2FLdIRiw74E7iTf imi3oLOaSxTAgaTlIVRtXL5Uaz0tV8zFgciIQsiM1cvyjLhshcfa3Os/JAn0WPMWRg2V UUVQ7buFALdXGWMkGO3x64HdMk0gjhb3LaghubUni2bhIkLNqcIXZpurF78VTUKcJLle hK+wcO4HpaFJdDDZP7oMO/rwBkKrivbOryITMgF52WIFX7MtC1ZBktDrBEZeoJ28SbR/ duSw== X-Gm-Message-State: AOAM531mPJSdpRq1fQsjlzyiOWQ/u1QCy0IfCvtQMyesgAUxAjBNE0hV 1xJqXjwq97PKuFrMMIkSg6LF+g== X-Google-Smtp-Source: ABdhPJyhRcLTZBa+XfteRdCO+FA9/OHAKBN+7g2rwoXy1FoYfOJS5iJftyYHXwOm4q6g6A12szEkJQ== X-Received: by 2002:a17:90a:4490:: with SMTP id t16mr102131pjg.183.1625853067635; Fri, 09 Jul 2021 10:51:07 -0700 (PDT) Received: from evgreen-glaptop.lan ([2601:646:c780:5ba8:8991:801d:8d8e:6534]) by smtp.gmail.com with ESMTPSA id n26sm7812310pgd.15.2021.07.09.10.51.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Jul 2021 10:51:07 -0700 (PDT) From: Evan Green To: Andrew Morton Cc: David Hildenbrand , Pavel Machek , Evan Green , Alex Shi , Alistair Popple , Jens Axboe , Johannes Weiner , Joonsoo Kim , "Matthew Wilcox (Oracle)" , Miaohe Lin , Michal Hocko , Minchan Kim , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2] mm: Enable suspend-only swap spaces Date: Fri, 9 Jul 2021 10:50:48 -0700 Message-Id: <20210709105012.v2.1.I09866d90c6de14f21223a03e9e6a31f8a02ecbaf@changeid> X-Mailer: git-send-email 2.31.0 MIME-Version: 1.0 Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=i7QnlekL; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf04.hostedemail.com: domain of evgreen@chromium.org designates 209.85.216.41 as permitted sender) smtp.mailfrom=evgreen@chromium.org X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: AC237500009F X-Stat-Signature: 9pwt4qa3za489t6i3qe3i7t5hamrawxa X-HE-Tag: 1625853068-818899 Content-Transfer-Encoding: quoted-printable 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: Currently it's not possible to enable hibernation without also enabling generic swap for a given swap area. These two use cases are not the same. For example there may be users who want to enable hibernation, but whose drives don't have the write endurance for generic swap activities. Add a new SWAP_FLAG_NOSWAP that adds a swap region but refuses to allow generic swapping to it. This region can still be wired up for use in suspend-to-disk activities, but will never have regular pages swapped to it. Swap regions with SWAP_FLAG_NOSWAP set will not appear in /proc/meminfo under SwapTotal and SwapFree, since they are not usable as general swap. Signed-off-by: Evan Green --- Changes in v2: - NOSWAP regions should not contribute to Swap stats in /proc/meminfo. [David] - Adjusted comment of SWAP_FLAG_NOSWAP [Pavel] - Note: Opted not to take Pavel's tag since enough has changed in this revision to warrant another look. - Call swap_entry_free() in swap_free to avoid NOSWAP leaks back into the general pool via swap_slots_cache [me]. include/linux/swap.h | 4 +++- mm/swapfile.c | 52 +++++++++++++++++++++++++++++++------------- 2 files changed, 40 insertions(+), 16 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 6f5a43251593c8..995466c9f16a76 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -28,10 +28,11 @@ struct pagevec; #define SWAP_FLAG_DISCARD 0x10000 /* enable discard for swap */ #define SWAP_FLAG_DISCARD_ONCE 0x20000 /* discard swap area at swapon-ti= me */ #define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after u= se */ +#define SWAP_FLAG_NOSWAP 0x80000 /* use only for hibernate, not swap */ =20 #define SWAP_FLAGS_VALID (SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \ SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \ - SWAP_FLAG_DISCARD_PAGES) + SWAP_FLAG_DISCARD_PAGES | SWAP_FLAG_NOSWAP) #define SWAP_BATCH 64 =20 static inline int current_is_kswapd(void) @@ -182,6 +183,7 @@ enum { SWP_PAGE_DISCARD =3D (1 << 10), /* freed swap page-cluster discards */ SWP_STABLE_WRITES =3D (1 << 11), /* no overwrite PG_writeback pages */ SWP_SYNCHRONOUS_IO =3D (1 << 12), /* synchronous IO is efficient */ + SWP_NOSWAP =3D (1 << 13), /* use only for suspend, not swap */ /* add others here before... */ SWP_SCANNING =3D (1 << 14), /* refcount in scan_swap_map */ }; diff --git a/mm/swapfile.c b/mm/swapfile.c index 1e07d1c776f2ae..d9ab39d32e55ec 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -697,7 +697,8 @@ static void swap_range_alloc(struct swap_info_struct = *si, unsigned long offset, if (si->inuse_pages =3D=3D si->pages) { si->lowest_bit =3D si->max; si->highest_bit =3D 0; - del_from_avail_list(si); + if (!(si->flags & SWP_NOSWAP)) + del_from_avail_list(si); } } =20 @@ -726,10 +727,12 @@ static void swap_range_free(struct swap_info_struct= *si, unsigned long offset, bool was_full =3D !si->highest_bit; =20 WRITE_ONCE(si->highest_bit, end); - if (was_full && (si->flags & SWP_WRITEOK)) + if (was_full && + ((si->flags & (SWP_WRITEOK | SWP_NOSWAP)) =3D=3D SWP_WRITEOK)) add_to_avail_list(si); } - atomic_long_add(nr_entries, &nr_swap_pages); + if (!(si->flags & SWP_NOSWAP)) + atomic_long_add(nr_entries, &nr_swap_pages); si->inuse_pages -=3D nr_entries; if (si->flags & SWP_BLKDEV) swap_slot_free_notify =3D @@ -1078,6 +1081,9 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entr= ies[], int entry_size) WARN(!(si->flags & SWP_WRITEOK), "swap_info %d in list but !SWP_WRITEOK\n", si->type); + WARN((si->flags & SWP_NOSWAP), + "swap_info %d in list but SWP_NOSWAP\n", + si->type); __del_from_avail_list(si); spin_unlock(&si->lock); goto nextsi; @@ -1338,8 +1344,12 @@ void swap_free(swp_entry_t entry) struct swap_info_struct *p; =20 p =3D _swap_info_get(entry); - if (p) - __swap_entry_free(p, entry); + if (p) { + if (p->flags & SWP_NOSWAP) + swap_entry_free(p, entry); + else + __swap_entry_free(p, entry); + } } =20 /* @@ -1783,8 +1793,10 @@ swp_entry_t get_swap_page_of_type(int type) =20 /* This is called for allocating swap entry, not cache */ spin_lock(&si->lock); - if ((si->flags & SWP_WRITEOK) && scan_swap_map_slots(si, 1, 1, &entry)) - atomic_long_dec(&nr_swap_pages); + if ((si->flags & SWP_WRITEOK) && scan_swap_map_slots(si, 1, 1, &entry))= { + if (!(si->flags & SWP_NOSWAP)) + atomic_long_dec(&nr_swap_pages); + } spin_unlock(&si->lock); fail: return entry; @@ -2454,8 +2466,6 @@ static void setup_swap_info(struct swap_info_struct= *p, int prio, static void _enable_swap_info(struct swap_info_struct *p) { p->flags |=3D SWP_WRITEOK; - atomic_long_add(p->pages, &nr_swap_pages); - total_swap_pages +=3D p->pages; =20 assert_spin_locked(&swap_lock); /* @@ -2469,7 +2479,11 @@ static void _enable_swap_info(struct swap_info_str= uct *p) * swap_info_struct. */ plist_add(&p->list, &swap_active_head); - add_to_avail_list(p); + if (!(p->flags & SWP_NOSWAP)) { + atomic_long_add(p->pages, &nr_swap_pages); + total_swap_pages +=3D p->pages; + add_to_avail_list(p); + } } =20 static void enable_swap_info(struct swap_info_struct *p, int prio, @@ -2564,7 +2578,9 @@ SYSCALL_DEFINE1(swapoff, const char __user *, speci= alfile) spin_unlock(&swap_lock); goto out_dput; } - del_from_avail_list(p); + if (!(p->flags & SWP_NOSWAP)) + del_from_avail_list(p); + spin_lock(&p->lock); if (p->prio < 0) { struct swap_info_struct *si =3D p; @@ -2581,8 +2597,10 @@ SYSCALL_DEFINE1(swapoff, const char __user *, spec= ialfile) least_priority++; } plist_del(&p->list, &swap_active_head); - atomic_long_sub(p->pages, &nr_swap_pages); - total_swap_pages -=3D p->pages; + if (!(p->flags & SWP_NOSWAP)) { + atomic_long_sub(p->pages, &nr_swap_pages); + total_swap_pages -=3D p->pages; + } p->flags &=3D ~SWP_WRITEOK; spin_unlock(&p->lock); spin_unlock(&swap_lock); @@ -3329,16 +3347,20 @@ SYSCALL_DEFINE2(swapon, const char __user *, spec= ialfile, int, swap_flags) if (swap_flags & SWAP_FLAG_PREFER) prio =3D (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; + + if (swap_flags & SWAP_FLAG_NOSWAP) + p->flags |=3D SWP_NOSWAP; enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map); =20 - pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s= %s%s%s%s\n", + pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s= %s%s%s%s%s\n", p->pages<<(PAGE_SHIFT-10), name->name, p->prio, nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), (p->flags & SWP_SOLIDSTATE) ? "SS" : "", (p->flags & SWP_DISCARDABLE) ? "D" : "", (p->flags & SWP_AREA_DISCARD) ? "s" : "", (p->flags & SWP_PAGE_DISCARD) ? "c" : "", - (frontswap_map) ? "FS" : ""); + (frontswap_map) ? "FS" : "", + (p->flags & SWP_NOSWAP) ? "N" : ""); =20 mutex_unlock(&swapon_mutex); atomic_inc(&proc_poll_event); --=20 2.31.0