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2023-07-27mm/damon/core-test: initialise context before test in damon_test_set_attrs()Feng Tang1-5/+5
Running kunit test for 6.5-rc1 hits one bug: ok 10 damon_test_update_monitoring_result general protection fault, probably for non-canonical address 0x1bffa5c419cfb81: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 PID: 110 Comm: kunit_try_catch Tainted: G N 6.5.0-rc2 #15 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:damon_set_attrs+0xb9/0x120 Code: f8 00 00 00 4c 8d 58 e0 48 39 c3 74 ba 41 ba 59 17 b7 d1 49 8b 43 10 4d 8d 4b 10 48 8d 70 e0 49 39 c1 74 50 49 8b 40 08 31 d2 <69> 4e 18 10 27 00 00 49 f7 30 31 d2 48 89 c5 89 c8 f7 f5 31 d2 89 RSP: 0000:ffffc900005bfd40 EFLAGS: 00010246 RAX: ffffffff81159fc0 RBX: ffffc900005bfeb8 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 01bffa5c419cfb69 RDI: ffffc900005bfd70 RBP: ffffc90000013c10 R08: ffffc900005bfdc0 R09: ffffffff81ff10ed R10: 00000000d1b71759 R11: ffffffff81ff10dd R12: ffffc90000013a78 R13: ffff88810eb78180 R14: ffffffff818297c0 R15: ffffc90000013c28 FS: 0000000000000000(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000002a1c001 CR4: 0000000000370ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> damon_test_set_attrs+0x63/0x1f0 kunit_generic_run_threadfn_adapter+0x17/0x30 kthread+0xfd/0x130 The problem seems to be related with the damon_ctx was used without being initialized. Fix it by adding the initialization. Link: https://lkml.kernel.org/r/20230718052811.1065173-1-feng.tang@intel.com Fixes: aa13779be6b7 ("mm/damon/core-test: add a test for damon_set_attrs()") Signed-off-by: Feng Tang <feng.tang@intel.com> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-24Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes.Andrew Morton1-0/+2
2023-06-20mm/damon/core-test: add a test for damon_set_attrs()SeongJae Park1-0/+24
Commit 5ff6e2fff88e ("mm/damon/core: fix divide error in damon_nr_accesses_to_accesses_bp()") fixed a bug by adding arguments validation in damon_set_attrs(). Add a unit test for the added validation to ensure the bug cannot occur again. Link: https://lkml.kernel.org/r/20230615183323.87561-1-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-20mm: ptep_get() conversionRyan Roberts3-6/+8
Convert all instances of direct pte_t* dereferencing to instead use ptep_get() helper. This means that by default, the accesses change from a C dereference to a READ_ONCE(). This is technically the correct thing to do since where pgtables are modified by HW (for access/dirty) they are volatile and therefore we should always ensure READ_ONCE() semantics. But more importantly, by always using the helper, it can be overridden by the architecture to fully encapsulate the contents of the pte. Arch code is deliberately not converted, as the arch code knows best. It is intended that arch code (arm64) will override the default with its own implementation that can (e.g.) hide certain bits from the core code, or determine young/dirty status by mixing in state from another source. Conversion was done using Coccinelle: ---- // $ make coccicheck \ // COCCI=ptepget.cocci \ // SPFLAGS="--include-headers" \ // MODE=patch virtual patch @ depends on patch @ pte_t *v; @@ - *v + ptep_get(v) ---- Then reviewed and hand-edited to avoid multiple unnecessary calls to ptep_get(), instead opting to store the result of a single call in a variable, where it is correct to do so. This aims to negate any cost of READ_ONCE() and will benefit arch-overrides that may be more complex. Included is a fix for an issue in an earlier version of this patch that was pointed out by kernel test robot. The issue arose because config MMU=n elides definition of the ptep helper functions, including ptep_get(). HUGETLB_PAGE=n configs still define a simple huge_ptep_clear_flush() for linking purposes, which dereferences the ptep. So when both configs are disabled, this caused a build error because ptep_get() is not defined. Fix by continuing to do a direct dereference when MMU=n. This is safe because for this config the arch code cannot be trying to virtualize the ptes because none of the ptep helpers are defined. Link: https://lkml.kernel.org/r/20230612151545.3317766-4-ryan.roberts@arm.com Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/oe-kbuild-all/202305120142.yXsNEo6H-lkp@intel.com/ Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Potapenko <glider@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Dave Airlie <airlied@gmail.com> Cc: Dimitri Sivanich <dimitri.sivanich@hpe.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: SeongJae Park <sj@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-20mm/pagewalkers: ACTION_AGAIN if pte_offset_map_lock() failsHugh Dickins1-4/+8
Simple walk_page_range() users should set ACTION_AGAIN to retry when pte_offset_map_lock() fails. No need to check pmd_trans_unstable(): that was precisely to avoid the possiblity of calling pte_offset_map() on a racily removed or inserted THP entry, but such cases are now safely handled inside it. Likewise there is no need to check pmd_none() or pmd_bad() before calling it. Link: https://lkml.kernel.org/r/c77d9d10-3aad-e3ce-4896-99e91c7947f3@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: SeongJae Park <sj@kernel.org> for mm/damon part Cc: Alistair Popple <apopple@nvidia.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Christoph Hellwig <hch@infradead.org> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Song Liu <song@kernel.org> Cc: Steven Price <steven.price@arm.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> Cc: Will Deacon <will@kernel.org> Cc: Yang Shi <shy828301@gmail.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Zack Rusin <zackr@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-12mm/damon/core: fix divide error in damon_nr_accesses_to_accesses_bp()Kefeng Wang1-0/+2
If 'aggr_interval' is smaller than 'sample_interval', max_nr_accesses in damon_nr_accesses_to_accesses_bp() becomes zero which leads to divide error, let's validate the values of them in damon_set_attrs() to fix it, which similar to others attrs check. Link: https://lkml.kernel.org/r/20230527032101.167788-1-wangkefeng.wang@huawei.com Fixes: 2f5bef5a590b ("mm/damon/core: update monitoring results for new monitoring attributes") Reported-by: syzbot+841a46899768ec7bec67@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=841a46899768ec7bec67 Link: https://lore.kernel.org/damon/00000000000055fc4e05fc975bc2@google.com/ Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-10mm/damon/ops-common: refactor to use {pte|pmd}p_clear_young_notify()Ryan Roberts1-20/+2
With the fix in place to atomically test and clear young on ptes and pmds, simplify the code to handle the clearing for both the primary mmu and the mmu notifier with a single API call. Link: https://lkml.kernel.org/r/20230602092949.545577-4-ryan.roberts@arm.com Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> Acked-by: Yu Zhao <yuzhao@google.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-10mm/damon/ops-common: atomically test and clear young on ptes and pmdsRyan Roberts4-16/+12
It is racy to non-atomically read a pte, then clear the young bit, then write it back as this could discard dirty information. Further, it is bad practice to directly set a pte entry within a table. Instead clearing young must go through the arch-provided helper, ptep_test_and_clear_young() to ensure it is modified atomically and to give the arch code visibility and allow it to check (and potentially modify) the operation. Link: https://lkml.kernel.org/r/20230602092949.545577-3-ryan.roberts@arm.com Fixes: 3f49584b262c ("mm/damon: implement primitives for the virtual memory address spaces"). Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Reviewed-by: SeongJae Park <sj@kernel.org> Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: Yu Zhao <yuzhao@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-05-03mm/damon/paddr: fix missing folio_sz update in damon_pa_young()Kefeng Wang1-4/+2
The *folio_sz in damon_pa_young() will be used(as last_folio_sz) by __damon_pa_check_access(), so it's need to be updated, fix missing branch. Link: https://lkml.kernel.org/r/20230308083311.120951-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-05-03mm/damon/paddr: minor refactor of damon_pa_mark_accessed_or_deactivate()Kefeng Wang1-4/+3
Omit one line by unified folio_put(), and make code more clear. Link: https://lkml.kernel.org/r/20230308083311.120951-3-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-05-03mm/damon/paddr: minor refactor of damon_pa_pageout()Kefeng Wang1-8/+5
Patch series "mm/damon/paddr: minor code improvement", v3. Unify folio_put() to make code more clear, and also fix minor issue in damon_pa_young(). This patch (of 3): Omit three lines by unified folio_put(), and make code more clear. Link: https://lkml.kernel.org/r/20230308083311.120951-1-wangkefeng.wang@huawei.com Link: https://lkml.kernel.org/r/20230308083311.120951-2-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-06mm/damon/sysfs: make more kobj_type structures constantThomas Weißschuh1-2/+2
Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.") the driver core allows the usage of const struct kobj_type. Take advantage of this to constify the structure definition to prevent modification at runtime. These structures were not constified in commit e56397e8c40d ("mm/damon/sysfs: make kobj_type structures constant") as they didn't exist when that patch was written. Link: https://lkml.kernel.org/r/20230324-b4-kobj_type-damon2-v1-1-48ddbf1c8fcf@weissschuh.net Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Reviewed-by: SeongJae Park <sj@kernel.org> Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-03-08mm/damon/paddr: fix folio_nr_pages() after folio_put() in ↵SeongJae Park1-1/+1
damon_pa_mark_accessed_or_deactivate() damon_pa_mark_accessed_or_deactivate() is accessing a folio via folio_nr_pages() after folio_put() for the folio has invoked. Fix it. Link: https://lkml.kernel.org/r/20230304193949.296391-3-sj@kernel.org Fixes: f70da5ee8fe1 ("mm/damon: convert damon_pa_mark_accessed_or_deactivate() to use folios") Signed-off-by: SeongJae Park <sj@kernel.org> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-03-08mm/damon/paddr: fix folio_size() call after folio_put() in damon_pa_young()SeongJae Park1-2/+1
Patch series "mm/damon/paddr: Fix folio-use-after-put bugs". There are two folio accesses after folio_put() in mm/damon/paddr.c file. Fix those. This patch (of 2): damon_pa_young() is accessing a folio via folio_size() after folio_put() for the folio has invoked. Fix it. Link: https://lkml.kernel.org/r/20230304193949.296391-1-sj@kernel.org Link: https://lkml.kernel.org/r/20230304193949.296391-2-sj@kernel.org Fixes: 397b0c3a584b ("mm/damon/paddr: remove folio_sz field from damon_pa_access_chk_result") Signed-off-by: SeongJae Park <sj@kernel.org> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Cc: <stable@vger.kernel.org> [6.2.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-28mm/damon/paddr: fix missing folio_put()andrew.yang1-4/+3
damon_get_folio() would always increase folio _refcount and folio_isolate_lru() would increase folio _refcount if the folio's lru flag is set. If an unevictable folio isolated successfully, there will be two more _refcount. The one from folio_isolate_lru() will be decreased in folio_puback_lru(), but the other one from damon_get_folio() will be left behind. This causes a pin page. Whatever the case, the _refcount from damon_get_folio() should be decreased. Link: https://lkml.kernel.org/r/20230222064223.6735-1-andrew.yang@mediatek.com Fixes: 57223ac29584 ("mm/damon/paddr: support the pageout scheme") Signed-off-by: andrew.yang <andrew.yang@mediatek.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> [5.16.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-20mm: change to return bool for folio_isolate_lru()Baolin Wang1-1/+1
Patch series "Change the return value for page isolation functions", v3. Now the page isolation functions did not return a boolean to indicate success or not, instead it will return a negative error when failed to isolate a page. So below code used in most places seem a boolean success/failure thing, which can confuse people whether the isolation is successful. if (folio_isolate_lru(folio)) continue; Moreover the page isolation functions only return 0 or -EBUSY, and most users did not care about the negative error except for few users, thus we can convert all page isolation functions to return a boolean value, which can remove the confusion to make code more clear. No functional changes intended in this patch series. This patch (of 4): Now the folio_isolate_lru() did not return a boolean value to indicate isolation success or not, however below code checking the return value can make people think that it was a boolean success/failure thing, which makes people easy to make mistakes (see the fix patch[1]). if (folio_isolate_lru(folio)) continue; Thus it's better to check the negative error value expilictly returned by folio_isolate_lru(), which makes code more clear per Linus's suggestion[2]. Moreover Matthew suggested we can convert the isolation functions to return a boolean[3], since most users did not care about the negative error value, and can also remove the confusing of checking return value. So this patch converts the folio_isolate_lru() to return a boolean value, which means return 'true' to indicate the folio isolation is successful, and 'false' means a failure to isolation. Meanwhile changing all users' logic of checking the isolation state. No functional changes intended. [1] https://lore.kernel.org/all/20230131063206.28820-1-Kuan-Ying.Lee@mediatek.com/T/#u [2] https://lore.kernel.org/all/CAHk-=wiBrY+O-4=2mrbVyxR+hOqfdJ=Do6xoucfJ9_5az01L4Q@mail.gmail.com/ [3] https://lore.kernel.org/all/Y+sTFqwMNAjDvxw3@casper.infradead.org/ Link: https://lkml.kernel.org/r/cover.1676424378.git.baolin.wang@linux.alibaba.com Link: https://lkml.kernel.org/r/8a4e3679ed4196168efadf7ea36c038f2f7d5aa9.1676424378.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: SeongJae Park <sj@kernel.org> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-14mm/damon/dbgfs: print DAMON debugfs interface deprecation messageSeongJae Park1-0/+19
DAMON debugfs interface has announced to be deprecated after >v5.15 LTS kernel is released. And, v6.1.y has announced to be an LTS[1]. Though the announcement was there for a while, some people might not noticed that so far. Also, some users could depend on it and have problems at movng to the alternative (DAMON sysfs interface). For such cases, warn DAMON debugfs interface deprecation with contacts to ask helps when any DAMON debugfs interface file is opened. [1] https://git.kernel.org/pub/scm/docs/kernel/website.git/commit/?id=332e9121320bc7461b2d3a79665caf153e51732c [sj@kernel.org: split DAMON debugfs file open warning message, per Randy] Link: https://lkml.kernel.org/r/20230209192009.7885-4-sj@kernel.org Link: https://lkml.kernel.org/r/20230210044838.63723-4-sj@kernel.org Link: https://lkml.kernel.org/r/20230209192009.7885-4-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-14mm/damon/Kconfig: add DAMON debugfs interface deprecation noticeSeongJae Park1-3/+4
DAMON debugfs interface has announced to be deprecated after >v5.15 LTS kernel is released. And, v6.1.y has announced to be an LTS[1]. Though the announcement was there for a while, some people might not noticed that so far. Also, some users could depend on it and have problems at movng to the alternative (DAMON sysfs interface). For such cases, note DAMON debugfs interface as deprecated, and contacts to ask helps on the Kconfig. [1] https://git.kernel.org/pub/scm/docs/kernel/website.git/commit/?id=332e9121320bc7461b2d3a79665caf153e51732c Link: https://lkml.kernel.org/r/20230209192009.7885-3-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-10mm/damon/sysfs: make kobj_type structures constantThomas Weißschuh4-23/+23
Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.") the driver core allows the usage of const struct kobj_type. Take advantage of this to constify the structure definitions to prevent modification at runtime. Link: https://lkml.kernel.org/r/20230207-kobj_type-damon-v1-1-9d4fea6a465b@weissschuh.net Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-10mm/damon/vaddr-test.h: stop using vma_mas_store() for maple tree storeLiam R. Howlett1-6/+14
Prepare for the removal of the vma_mas_store() function by open coding the maple tree store in this test code. Set the range of the maple state and call the store function directly. Link: https://lkml.kernel.org/r/20230120162650.984577-31-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> Reported-by: kernel test robot <lkp@intel.com> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-03mm/damon/core-test: add a test for damon_update_monitoring_results()SeongJae Park1-0/+30
Add a simple unit test for damon_update_monitoring_results() function. Link: https://lkml.kernel.org/r/20230119013831.1911-4-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Brendan Higgins <brendanhiggins@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-03mm/damon/core: update monitoring results for new monitoring attributesSeongJae Park1-0/+71
region->nr_accesses is the number of sampling intervals in the last aggregation interval that access to the region has found, and region->age is the number of aggregation intervals that its access pattern has maintained. Hence, the real meaning of the two fields' values is depending on current sampling and aggregation intervals. This means the values need to be updated for every sampling and/or aggregation intervals updates. As DAMON core doesn't, it is a duty of in-kernel DAMON framework applications like DAMON sysfs interface, or the userspace users. Handling it in userspace or in-kernel DAMON application is complicated, inefficient, and repetitive compared to doing the update in DAMON core. Do the update in DAMON core. Link: https://lkml.kernel.org/r/20230119013831.1911-3-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Brendan Higgins <brendanhiggins@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-03mm/damon/core: skip apply schemes if emptyHuaisheng Ye1-1/+2
Sometimes there is no scheme in damon's context, for example just use damo record to monitor workload's data access pattern. If current damon context doesn't have any scheme in the list, kdamond has no need to iterate over list of all targets and regions but do nothing. So, skip apply schemes when ctx->schemes is empty. Link: https://lkml.kernel.org/r/20230116062347.1148553-1-huaisheng.ye@intel.com Signed-off-by: Huaisheng Ye <huaisheng.ye@intel.com> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/sysfs-schemes: use strscpy() to instead of strncpy()Xu Panda1-2/+1
The implementation of strscpy() is more robust and safer. That's now the recommended way to copy NUL-terminated strings. Link: https://lkml.kernel.org/r/202301091946553770006@zte.com.cn Signed-off-by: Xu Panda <xu.panda@zte.com.cn> Signed-off-by: Yang Yang <yang.yang29@zte.com.cn> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/paddr: remove damon_pa_access_chk_result structSeongJae Park1-17/+11
'damon_pa_access_chk_result' struct contains only one field. Use a variable instead. Link: https://lkml.kernel.org/r/20230109213335.62525-7-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/paddr: remove folio_sz field from damon_pa_access_chk_resultSeongJae Park1-6/+1
DAMON physical address space monitoring operations set gets and saves size of the folio for a given physical address inside rmap walks, but it can be directly caluclated outside of the walks. Remove the 'folio_sz' field from 'damon_pa_access_chk_result struct' and calculate the size directly from outside of the walks. Link: https://lkml.kernel.org/r/20230109213335.62525-6-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/paddr: rename 'damon_pa_access_chk_result->page_sz' to 'folio_sz'SeongJae Park1-10/+11
DAMON's physical address space monitoring operations set is using folio now. Rename 'damon_pa_access_chk_result->page_sz' to reflect the fact. Link: https://lkml.kernel.org/r/20230109213335.62525-5-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/vaddr: record appropriate folio size when the access is not foundSeongJae Park1-9/+6
DAMON virtual address spaces monitoring operations set doesn't set folio size of the access checked address if access is not found. It could result in unnecessary and inefficient repeated check. Appropriately set the size regardless of access check result. Link: https://lkml.kernel.org/r/20230109213335.62525-4-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/vaddr: support folio of neither HPAGE_PMD_SIZE nor PAGE_SIZESeongJae Park1-1/+1
DAMON virtual address space monitoring operations set treats folios having non-HPAGE_PMD_SIZE size as having PAGE_SIZE size. Use the exact size of the folio. Link: https://lkml.kernel.org/r/20230109213335.62525-3-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/vaddr: rename 'damon_young_walk_private->page_sz' to 'folio_sz'SeongJae Park1-10/+11
Patch series "mm/damon/{v,p}addr: misc fixups for folio usage". DAMON's monitoring operations set for the virtual and the physical address spaces use folio now, but some code is not reflecting the fact. Further cleanup the code for folio usage. This patch (of 6): DAMON's virtual address space monitoring operations set is using folio now. Rename 'damon_pa_access_chk_result->page_sz' to reflect the fact. Link: https://lkml.kernel.org/r/20230109213335.62525-1-sj@kernel.org Link: https://lkml.kernel.org/r/20230109213335.62525-2-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/vaddr: convert hugetlb related functions to use a folioKefeng Wang1-10/+10
Convert damon_hugetlb_mkold() and damon_young_hugetlb_entry() to use a folio. Link: https://lkml.kernel.org/r/20221230070849.63358-9-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon: remove unneeded damon_get_page()Kefeng Wang1-7/+0
After all damon_get_page() callers are converted to damon_get_folio(), remove unneeded wrapper damon_get_page(). Link: https://lkml.kernel.org/r/20221230070849.63358-8-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/vaddr: convert damon_young_pmd_entry() to use a folioKefeng Wang1-9/+9
With damon_get_folio(), let's convert damon_young_pmd_entry() to use a folio. Link: https://lkml.kernel.org/r/20221230070849.63358-7-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/paddr: convert damon_pa_*() to use a folioKefeng Wang1-32/+26
With damon_get_folio(), let's convert all the damon_pa_*() to use a folio. Link: https://lkml.kernel.org/r/20221230070849.63358-6-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon: convert damon_ptep/pmdp_mkold() to use a folioKefeng Wang1-10/+10
With damon_get_folio(), let's convert damon_ptep_mkold() and damon_pmdp_mkold() to use a folio. Link: https://lkml.kernel.org/r/20221230070849.63358-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon: introduce damon_get_folio()Kefeng Wang2-8/+19
Introduce damon_get_folio(), and the temporary wrapper function damon_get_page(), which help us to convert damon related functions to use folios, and it will be dropped once the conversion is completed. Link: https://lkml.kernel.org/r/20221230070849.63358-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/swap: convert deactivate_page() to folio_deactivate()Vishal Moola (Oracle)1-1/+1
Deactivate_page() has already been converted to use folios, this change converts it to take in a folio argument instead of calling page_folio(). It also renames the function folio_deactivate() to be more consistent with other folio functions. [akpm@linux-foundation.org: fix left-over comments, per Yu Zhao] Link: https://lkml.kernel.org/r/20221221180848.20774-5-vishal.moola@gmail.com Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon: convert damon_pa_mark_accessed_or_deactivate() to use foliosVishal Moola (Oracle)1-6/+8
This change replaces 2 calls to compound_head() from put_page() and 1 call from mark_page_accessed() with one from page_folio(). This is in preparation for the conversion of deactivate_page() to folio_deactivate(). Link: https://lkml.kernel.org/r/20221221180848.20774-4-vishal.moola@gmail.com Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com> Reviewed-by: SeongJae Park <sj@kernel.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/sysfs-schemes: implement scheme filtersSeongJae Park1-1/+92
Implement scheme filters functionality of DAMON sysfs interface by making the code reads the values of files under the filter directories and pass that to DAMON using DAMON kernel API. [sj@kernel.org: fix leaking a filter for wrong cgroup path] Link: https://lkml.kernel.org/r/20221219171807.55708-2-sj@kernel.org [sj@kernel.org: return an error for filter memcg path id lookup failure] Link: https://lkml.kernel.org/r/20221219171807.55708-3-sj@kernel.org Link: https://lkml.kernel.org/r/20221205230830.144349-9-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/sysfs-schemes: connect filter directory and filters directorySeongJae Park1-0/+68
Implement 'nr_filters' file under 'filters' directory, which will be used to populate specific number of 'filter' directory under the directory, similar to other 'nr_*' files in DAMON sysfs interface. Link: https://lkml.kernel.org/r/20221205230830.144349-8-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/sysfs-schemes: implement filter directorySeongJae Park1-0/+128
Implement DAMOS filter directory which will be located under the filters directory. The directory provides three files, namely type, matching, and memcg_path. 'type' and 'matching' will be directly connected to the fields of 'struct damos_filter' having same name. 'memcg_path' will receive the path of the memory cgroup of the interest and later converted to memcg id when it's committed. Link: https://lkml.kernel.org/r/20221205230830.144349-7-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/sysfs-schemes: implement filters directorySeongJae Park1-1/+84
DAMOS filters are currently supported by only DAMON kernel API. To expose the feature to user space, implement a DAMON sysfs directory named 'filters' under each scheme directory. Please note that this is implementing only the directory. Following commits will implement more files and directories, and finally connect the DAMOS filters feature. Link: https://lkml.kernel.org/r/20221205230830.144349-6-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/reclaim: add a parameter called skip_anon for avoiding anonymous ↵SeongJae Park1-0/+19
pages reclamation In some cases, for example if users have confidence at anonymous pages management or the swap device is too slow, users would want to avoid DAMON_RECLAIM swapping the anonymous pages out. For such case, add yet another DAMON_RECLAIM parameter, namely 'skip_anon'. When it is set as 'Y', DAMON_RECLAIM will avoid reclaiming anonymous pages using a DAMOS filter. Link: https://lkml.kernel.org/r/20221205230830.144349-4-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/paddr: support DAMOS filtersSeongJae Park1-9/+62
Implement support of the DAMOS filters in the physical address space monitoring operations set, for all DAMOS actions that it supports including 'pageout', 'lru_prio', and 'lru_deprio'. Link: https://lkml.kernel.org/r/20221205230830.144349-3-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19mm/damon/core: implement damos filterSeongJae Park1-0/+39
Patch series "implement DAMOS filtering for anon pages and/or specific memory cgroups" DAMOS let users do system operations in a data access pattern oriented way. The data access pattern, which is extracted by DAMON, is somewhat accurate more than what user space could know in many cases. However, in some situation, users could know something more than the kernel about the pattern or some special requirements for some types of memory or processes. For example, some users would have slow swap devices and knows latency-ciritical processes and therefore want to use DAMON-based proactive reclamation (DAMON_RECLAIM) for only non-anonymous pages of non-latency-critical processes. For such restriction, users could exclude the memory regions from the initial monitoring regions and use non-dynamic monitoring regions update monitoring operations set including fvaddr and paddr. They could also adjust the DAMOS target access pattern. For dynamically changing memory layout and access pattern, those would be not enough. To help the case, add an interface, namely DAMOS filters, which can be used to avoid the DAMOS actions be applied to specific types of memory, to DAMON kernel API (damon.h). At the moment, it supports filtering anonymous pages and/or specific memory cgroups in or out for each DAMOS scheme. This patchset adds the support for all DAMOS actions that 'paddr' monitoring operations set supports ('pageout', 'lru_prio', and 'lru_deprio'), and the functionality is exposed via DAMON kernel API (damon.h) the DAMON sysfs interface (/sys/kernel/mm/damon/admins/), and DAMON_RECLAIM module parameters. Patches Sequence ---------------- First patch implements DAMOS filter interface to DAMON kernel API. Second patch makes the physical address space monitoring operations set to support the filters from all supporting DAMOS actions. Third patch adds anonymous pages filter support to DAMON_RECLAIM, and the fourth patch documents the DAMON_RECLAIM's new feature. Fifth to seventh patches implement DAMON sysfs files for support of the filters, and eighth patch connects the file to use DAMOS filters feature. Ninth patch adds simple self test cases for DAMOS filters of the sysfs interface. Finally, following two patches (tenth and eleventh) document the new features and interfaces. This patch (of 11): DAMOS lets users do system operation in a data access pattern oriented way. The data access pattern, which is extracted by DAMON, is somewhat accurate more than what user space could know in many cases. However, in some situation, users could know something more than the kernel about the pattern or some special requirements for some types of memory or processes. For example, some users would have slow swap devices and knows latency-ciritical processes and therefore want to use DAMON-based proactive reclamation (DAMON_RECLAIM) for only non-anonymous pages of non-latency-critical processes. For such restriction, users could exclude the memory regions from the initial monitoring regions and use non-dynamic monitoring regions update monitoring operations set including fvaddr and paddr. They could also adjust the DAMOS target access pattern. For dynamically changing memory layout and access pattern, those would be not enough. To help the case, add an interface, namely DAMOS filters, which can be used to avoid the DAMOS actions be applied to specific types of memory, to DAMON kernel API (damon.h). At the moment, it supports filtering anonymous pages and/or specific memory cgroups in or out for each DAMOS scheme. Note that this commit adds only the interface to the DAMON kernel API. The impelmentation should be made in the monitoring operations sets, and following commits will add that. Link: https://lkml.kernel.org/r/20221205230830.144349-1-sj@kernel.org Link: https://lkml.kernel.org/r/20221205230830.144349-2-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-12-01mm/damon: use kstrtobool() instead of strtobool()Christophe JAILLET2-2/+4
strtobool() is the same as kstrtobool(). However, the latter is more used within the kernel. In order to remove strtobool() and slightly simplify kstrtox.h, switch to the other function name. While at it, include the corresponding header file (<linux/kstrtox.h>) Link: https://lkml.kernel.org/r/ed2b46489a513988688decb53850339cc228940c.1667336095.git.christophe.jaillet@wanadoo.fr Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-12-01mm/damon/sysfs-schemes: implement DAMOS-tried regions clear commandSeongJae Park3-1/+37
When there are huge number of DAMON regions that specific scheme actions are tried to be applied, directories and files under 'tried_regions' scheme directory could waste some memory. Add another special input keyword ('clear_schemes_tried_regions') for 'state' file of each kdamond sysfs directory that can be used for cleanup of the 'tried_regions' sub-directories. [sj@kernel.org: skip regions clearing if the scheme directory was removed] Link: https://lkml.kernel.org/r/20221114182954.4745-3-sj@kernel.org Link: https://lkml.kernel.org/r/20221101220328.95765-6-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-12-01mm/damon/sysfs: implement DAMOS tried regions update commandSeongJae Park3-2/+141
Implement the code for filling the data of 'tried_regions' DAMON sysfs directory. With this commit, DAMON sysfs interface users can write a special keyword, 'update_schemes_tried_regions' to the corresponding 'state' file of the kdamond. Then, DAMON sysfs interface will collect the tried regions information using the 'before_damos_apply()' callback for one aggregation interval and populate scheme region directories with the values. [sj@kernel.org: skip tried regions update if the scheme directory was removed] Link: https://lkml.kernel.org/r/20221114182954.4745-2-sj@kernel.org Link: https://lkml.kernel.org/r/20221101220328.95765-5-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-12-01mm/damon/sysfs-schemes: implement scheme region directorySeongJae Park1-1/+122
Implement region directories under 'tried_regions' directory of each scheme DAMON sysfs directory. This directory will provide the address range, the monitored access frequency ('nr_accesses'), and the age of each DAMON region that corresponding DAMON-based operation scheme has tried to be applied. Note that this commit doesn't implement the code for filling the data but only the sysfs directory. Link: https://lkml.kernel.org/r/20221101220328.95765-4-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-12-01mm/damon/sysfs-schemes: implement schemes/tried_regions directorySeongJae Park1-0/+57
For efficient and simple query-like DAMON monitoring results readings and deep level investigations of DAMOS, DAMON kernel API (include/linux/damon.h) users can use 'before_damos_apply' DAMON callback. However, DAMON sysfs interface users don't have such option. Add a directory, namely 'tried_regions', under each scheme directory to use it as the interface for the purpose. Note that this commit is implementing only the directory but the data filling. After the data filling change is made, users will be able to signal DAMON to fill the directory with the regions that corresponding scheme has tried to be applied. By setting the access pattern of the scheme, users could do the efficient query-like monitoring. Link: https://lkml.kernel.org/r/20221101220328.95765-3-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>