Changes in hugetlb_cgroup.h

59838b25 - mm, hugetlb: remove HUGETLB_CGROUP_MIN_ORDER

Wed, 04 Oct 2023 15:32:48 +0000

mm, hugetlb: remove HUGETLB_CGROUP_MIN_ORDEROriginally, hugetlb_cgroup was the only hugetlb user of tail pagestructure fields. So, the code defined and checked againstHUGETLB_CGROUP_MIN_ORDER to make sure pages weren't too small to use.However, by now, tail page #2 is used to store hugetlb hwpoison andsubpool information as well. In other words, without that tail pagehugetlb doesn't work.Acknowledge this fact by getting rid of HUGETLB_CGROUP_MIN_ORDER andchecks against it. Instead, just check for the minimum viable page orderat hstate creation time.Link: https://lkml.kernel.org/r/20231004153248.3842997-1-fvdl@google.comSigned-off-by: Frank van der Linden Reviewed-by: Mike Kravetz Cc: Muchun Song Signed-off-by: Andrew Morton List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

ff7d853b - mm/hugetlb: increase use of folios in alloc_huge_page()

Fri, 13 Jan 2023 22:30:54 +0000

mm/hugetlb: increase use of folios in alloc_huge_page()Change hugetlb_cgroup_commit_charge{,_rsvd}(), dequeue_huge_page_vma() andalloc_buddy_huge_page_with_mpol() to use folios so alloc_huge_page() iscleaned by operating on folios until its return.Link: https://lkml.kernel.org/r/20230113223057.173292-6-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar Reviewed-by: Mike Kravetz Cc: John Hubbard Cc: Matthew Wilcox Cc: Muchun Song Signed-off-by: Andrew Morton List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

dad6a5eb - mm,hugetlb: use folio fields in second tail page

Thu, 03 Nov 2022 01:48:45 +0000

mm,hugetlb: use folio fields in second tail pagePatch series "mm,huge,rmap: unify and speed up compound mapcounts".This patch (of 3):We want to declare one more int in the first tail of a compound page: thatfirst tail page being valuable property, since every compound page has afirst tail, but perhaps no more than that.No problem on 64-bit: there is already space for it. No problem with32-bit THPs: 5.18 commit 5232c63f46fd ("mm: Make compound_pincount alwaysavailable") kindly cleared the space for it, apparently not realizing thatonly 64-bit architectures enable CONFIG_THP_SWAP (whose use of tailpage->private might conflict) - but make sure of that in its Kconfig.But hugetlb pages use tail page->private of the first tail page for asubpool pointer, which will conflict; and they also use page->private ofthe 2nd, 3rd and 4th tails.Undo "mm: add private field of first tail to struct page and structfolio"'s recent addition of private_1 to the folio tail: instead addhugetlb_subpool, hugetlb_cgroup, hugetlb_cgroup_rsvd, hugetlb_hwpoison toa second tail page of the folio: THP has long been using several fields ofthat tail, so make better use of it for hugetlb too. This is not how ageneric folio should be declared in future, but it is an effectivetransitional way to make use of it.Delete the SUBPAGE_INDEX stuff, but keep __NR_USED_SUBPAGE: now 3.[hughd@google.com: prefix folio's page_1 and page_2 with double underscore, give folio's _flags_2 and _head_2 a line documentation each] Link: https://lkml.kernel.org/r/9e2cb6b-5b58-d3f2-b5ee-5f8a14e8f10@google.comLink: https://lkml.kernel.org/r/5f52de70-975-e94f-f141-543765736181@google.comLink: https://lkml.kernel.org/r/3818cc9a-9999-d064-d778-9c94c5911e6@google.comSigned-off-by: Hugh Dickins Acked-by: Kirill A. Shutemov Cc: David Hildenbrand Cc: James Houghton Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Mike Kravetz Cc: Mina Almasry Cc: Muchun Song Cc: Naoya Horiguchi Cc: Peter Xu Cc: Sidhartha Kumar Cc: Vlastimil Babka Cc: Yang Shi Cc: Zach O'Keefe Signed-off-by: Andrew Morton List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

d4ab0316 - mm/hugetlb_cgroup: convert hugetlb_cgroup_uncharge_page() to folios

Tue, 01 Nov 2022 22:30:57 +0000

mm/hugetlb_cgroup: convert hugetlb_cgroup_uncharge_page() to foliosContinue to use a folio inside free_huge_page() by convertinghugetlb_cgroup_uncharge_page*() to folios.Link: https://lkml.kernel.org/r/20221101223059.460937-8-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar Reviewed-by: Mike Kravetz Reviewed-by: Muchun Song Cc: Aneesh Kumar K.V Cc: Bui Quang Minh Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Mina Almasry Signed-off-by: Andrew Morton List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

29f39430 - mm/hugetlb_cgroup: convert hugetlb_cgroup_migrate to folios

Tue, 01 Nov 2022 22:30:54 +0000

mm/hugetlb_cgroup: convert hugetlb_cgroup_migrate to foliosCleans up intermediate page to folio conversion code inhugetlb_cgroup_migrate() by changing its arguments from pages to folios.Link: https://lkml.kernel.org/r/20221101223059.460937-5-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar Reviewed-by: Mike Kravetz Reviewed-by: Muchun Song Cc: Aneesh Kumar K.V Cc: Bui Quang Minh Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Mina Almasry Signed-off-by: Andrew Morton List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

de656ed3 - mm/hugetlb_cgroup: convert set_hugetlb_cgroup*() to folios

Tue, 01 Nov 2022 22:30:53 +0000

mm/hugetlb_cgroup: convert set_hugetlb_cgroup*() to foliosAllows __prep_new_huge_page() to operate on a folio by convertingset_hugetlb_cgroup*() to take in a folio.Link: https://lkml.kernel.org/r/20221101223059.460937-4-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar Reviewed-by: Mike Kravetz Cc: Aneesh Kumar K.V Cc: Bui Quang Minh Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Mina Almasry Cc: Muchun Song Signed-off-by: Andrew Morton List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

f074732d - mm/hugetlb_cgroup: convert hugetlb_cgroup_from_page() to folios

Tue, 01 Nov 2022 22:30:52 +0000

mm/hugetlb_cgroup: convert hugetlb_cgroup_from_page() to foliosIntroduce folios in __remove_hugetlb_page() by convertinghugetlb_cgroup_from_page() to use folios.Also gets rid of unsed hugetlb_cgroup_from_page_resv() function.Link: https://lkml.kernel.org/r/20221101223059.460937-3-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar Reviewed-by: Muchun Song Cc: Aneesh Kumar K.V Cc: Bui Quang Minh Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Mike Kravetz Cc: Mina Almasry Signed-off-by: Andrew Morton List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

a098c977 - mm/hugetlb_cgroup: convert __set_hugetlb_cgroup() to folios

Tue, 01 Nov 2022 22:30:51 +0000

mm/hugetlb_cgroup: convert __set_hugetlb_cgroup() to foliosPatch series "convert hugetlb_cgroup helper functions to folios", v2.This patch series continues the conversion of hugetlb code from beingmanaged in pages to folios by converting many of the hugetlb_cgroup helperfunctions to use folios. This allows the core hugetlb functions to passin a folio to these helper functions.This patch (of 9);Change __set_hugetlb_cgroup() to use folios so it is explicit that thefunction operates on a head page.Link: https://lkml.kernel.org/r/20221101223059.460937-1-sidhartha.kumar@oracle.comLink: https://lkml.kernel.org/r/20221101223059.460937-2-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar Reviewed-by: Mike Kravetz Reviewed-by: Muchun Song Cc: Aneesh Kumar K.V Cc: Bui Quang Minh Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Mina Almasry Signed-off-by: Andrew Morton List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

736a8ccc - hugetlb_cgroup: remove unneeded return value

Fri, 29 Jul 2022 08:01:04 +0000

hugetlb_cgroup: remove unneeded return valueThe return value of set_hugetlb_cgroup and set_hugetlb_cgroup_rsvd arealways ignored. Remove them to clean up the code.Link: https://lkml.kernel.org/r/20220729080106.12752-4-linmiaohe@huawei.comSigned-off-by: Miaohe Lin Reviewed-by: Mike Kravetz Cc: Mina Almasry Signed-off-by: Andrew Morton List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

f4776199 - hugetlb: add hugetlb.*.numa_stat file

Fri, 14 Jan 2022 22:07:48 +0000

hugetlb: add hugetlb.*.numa_stat fileFor hugetlb backed jobs/VMs it's critical to understand the numainformation for the memory backing these jobs to deliver optimalperformance.Currently this technically can be queried from /proc/self/numa_maps, butthere are significant issues with that. Namely:1. Memory can be mapped or unmapped.2. numa_maps are per process and need to be aggregated across all processes in the cgroup. For shared memory this is more involved as the userspace needs to make sure it doesn't double count shared mappings.3. I believe querying numa_maps needs to hold the mmap_lock which adds to the contention on this lock.For these reasons I propose simply adding hugetlb.*.numa_stat file, which shows the numa information of the cgroup similarly to memory.numa_stat.On cgroup-v2: cat /sys/fs/cgroup/unified/test/hugetlb.2MB.numa_stat total=2097152 N0=2097152 N1=0On cgroup-v1: cat /sys/fs/cgroup/hugetlb/test/hugetlb.2MB.numa_stat total=2097152 N0=2097152 N1=0 hierarichal_total=2097152 N0=2097152 N1=0This patch was tested manually by allocating hugetlb memory and queryingthe hugetlb.*.numa_stat file of the cgroup and its parents.[colin.i.king@googlemail.com: fix spelling mistake "hierarichal" -> "hierarchical"] Link: https://lkml.kernel.org/r/20211125090635.23508-1-colin.i.king@gmail.com[keescook@chromium.org: fix copy/paste array assignment] Link: https://lkml.kernel.org/r/20211203065647.2819707-1-keescook@chromium.orgLink: https://lkml.kernel.org/r/20211123001020.4083653-1-almasrymina@google.comSigned-off-by: Mina Almasry Signed-off-by: Colin Ian King Signed-off-by: Kees Cook Reviewed-by: Shakeel Butt Reviewed-by: Muchun Song Reviewed-by: Mike Kravetz Cc: Shuah Khan Cc: Miaohe Lin Cc: Oscar Salvador Cc: Michal Hocko Cc: David Rientjes Cc: Jue Wang Cc: Yang Yao Cc: Joanna Li Cc: Cannon Matthews Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

afe041c2 - hugetlb: fix hugetlb cgroup refcounting during mremap

Sat, 20 Nov 2021 00:43:40 +0000

hugetlb: fix hugetlb cgroup refcounting during mremapWhen hugetlb_vm_op_open() is called during copy_vma(), we may take thereference to resv_map->css. Later, when clearing the reservationpointer of old_vma after transferring it to new_vma, we forget to dropthe reference to resv_map->css. This leads to a reference leak of css.Fixes this by adding a check to drop reservation css reference inclear_vma_resv_huge_pages()Link: https://lkml.kernel.org/r/20211113154412.91134-1-minhquangbui99@gmail.comFixes: 550a7d60bd5e35 ("mm, hugepages: add mremap() support for hugepage backed vma")Signed-off-by: Bui Quang Minh Reviewed-by: Mike Kravetz Reviewed-by: Mina Almasry Cc: Miaohe Lin Cc: Michal Hocko Cc: Muchun Song Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

09a26e83 - hugetlb: fix hugetlb cgroup refcounting during vma split

Thu, 02 Sep 2021 21:58:53 +0000

hugetlb: fix hugetlb cgroup refcounting during vma splitGuillaume Morin reported hitting the following WARNING followed by GPF orNULL pointer deference either in cgroups_destroy or in the kill_css path.: percpu ref (css_release) <= 0 (-1) after switching to atomic WARNING: CPU: 23 PID: 130 at lib/percpu-refcount.c:196 percpu_ref_switch_to_atomic_rcu+0x127/0x130 CPU: 23 PID: 130 Comm: ksoftirqd/23 Kdump: loaded Tainted: G O 5.10.60 #1 RIP: 0010:percpu_ref_switch_to_atomic_rcu+0x127/0x130 Call Trace: rcu_core+0x30f/0x530 rcu_core_si+0xe/0x10 __do_softirq+0x103/0x2a2 run_ksoftirqd+0x2b/0x40 smpboot_thread_fn+0x11a/0x170 kthread+0x10a/0x140 ret_from_fork+0x22/0x30Upon further examination, it was discovered that the css structure wasassociated with hugetlb reservations.For private hugetlb mappings the vma points to a reserve map thatcontains a pointer to the css. At mmap time, reservations are set upand a reference to the css is taken. This reference is dropped in thevma close operation; hugetlb_vm_op_close. However, if a vma is split noadditional reference to the css is taken yet hugetlb_vm_op_close will becalled twice for the split vma resulting in an underflow.Fix by taking another reference in hugetlb_vm_op_open. Note that thereference is only taken for the owner of the reserve map. In the morecommon fork case, the pointer to the reserve map is cleared fornon-owning vmas.Link: https://lkml.kernel.org/r/20210830215015.155224-1-mike.kravetz@oracle.comFixes: e9fe92ae0cd2 ("hugetlb_cgroup: add reservation accounting for private mappings")Signed-off-by: Mike Kravetz Reported-by: Guillaume Morin Suggested-by: Guillaume Morin Tested-by: Guillaume Morin Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

cd39d4e9 - mm: hugetlb: gather discrete indexes of tail page

Thu, 01 Jul 2021 01:47:09 +0000

mm: hugetlb: gather discrete indexes of tail pageFor HugeTLB page, there are more metadata to save in the struct page. Butthe head struct page cannot meet our needs, so we have to abuse other tailstruct page to store the metadata. In order to avoid conflicts caused bysubsequent use of more tail struct pages, we can gather these discreteindexes of tail struct page. In this case, it will be easier to add a newtail page index later.Link: https://lkml.kernel.org/r/20210510030027.56044-4-songmuchun@bytedance.comSigned-off-by: Muchun Song Reviewed-by: Oscar Salvador Reviewed-by: Miaohe Lin Tested-by: Chen Huang Tested-by: Bodeddula Balasubramaniam Acked-by: Michal Hocko Reviewed-by: Mike Kravetz Cc: Alexander Viro Cc: Andy Lutomirski Cc: Anshuman Khandual Cc: Balbir Singh Cc: Barry Song Cc: Borislav Petkov Cc: Dave Hansen Cc: David Hildenbrand Cc: David Rientjes Cc: HORIGUCHI NAOYA Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Joao Martins Cc: Joerg Roedel Cc: Jonathan Corbet Cc: Matthew Wilcox Cc: Mina Almasry Cc: Oliver Neukum Cc: Paul E. McKenney Cc: Pawan Gupta Cc: Peter Zijlstra Cc: Randy Dunlap Cc: Thomas Gleixner Cc: Xiongchun Duan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

d85aecf2 - hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings

Thu, 25 Mar 2021 04:37:17 +0000

hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappingsThe current implementation of hugetlb_cgroup for shared mappings couldhave different behavior. Consider the following two scenarios: 1.Assume initial css reference count of hugetlb_cgroup is 1: 1.1 Call hugetlb_reserve_pages with from = 1, to = 2. So css reference count is 2 associated with 1 file_region. 1.2 Call hugetlb_reserve_pages with from = 2, to = 3. So css reference count is 3 associated with 2 file_region. 1.3 coalesce_file_region will coalesce these two file_regions into one. So css reference count is 3 associated with 1 file_region now. 2.Assume initial css reference count of hugetlb_cgroup is 1 again: 2.1 Call hugetlb_reserve_pages with from = 1, to = 3. So css reference count is 2 associated with 1 file_region.Therefore, we might have one file_region while holding one or more cssreference counts. This inconsistency could lead to imbalanced css_get()and css_put() pair. If we do css_put one by one (i.g. hole punch case),scenario 2 would put one more css reference. If we do css_put alltogether (i.g. truncate case), scenario 1 will leak one css reference.The imbalanced css_get() and css_put() pair would result in a non-zeroreference when we try to destroy the hugetlb cgroup. The hugetlb cgroupdirectory is removed __but__ associated resource is not freed. Thismight result in OOM or can not create a new hugetlb cgroup in a busyworkload ultimately.In order to fix this, we have to make sure that one file_region musthold exactly one css reference. So in coalesce_file_region case, weshould release one css reference before coalescence. Also only put cssreference when the entire file_region is removed.The last thing to note is that the caller of region_add() will only holdone reference to h_cg->css for the whole contiguous reservation region.But this area might be scattered when there are already somefile_regions reside in it. As a result, many file_regions may share onlyone h_cg->css reference. In order to ensure that one file_region musthold exactly one css reference, we should do css_get() for eachfile_region and release the reference held by caller when they are done.[linmiaohe@huawei.com: fix imbalanced css_get and css_put pair for shared mappings] Link: https://lkml.kernel.org/r/20210316023002.53921-1-linmiaohe@huawei.comLink: https://lkml.kernel.org/r/20210301120540.37076-1-linmiaohe@huawei.comFixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings")Reported-by: kernel test robot (auto build test ERROR)Signed-off-by: Miaohe Lin Reviewed-by: Mike Kravetz Cc: Aneesh Kumar K.V Cc: Wanpeng Li Cc: Mina Almasry Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

075a61d0 - hugetlb_cgroup: add accounting for shared mappings

Thu, 02 Apr 2020 04:11:28 +0000

hugetlb_cgroup: add accounting for shared mappingsFor shared mappings, the pointer to the hugetlb_cgroup to uncharge livesin the resv_map entries, in file_region->reservation_counter.After a call to region_chg, we charge the approprate hugetlb_cgroup, andif successful, we pass on the hugetlb_cgroup info to a follow upregion_add call. When a file_region entry is added to the resv_map viaregion_add, we put the pointer to that cgroup infile_region->reservation_counter. If charging doesn't succeed, we reportthe error to the caller, so that the kernel fails the reservation.On region_del, which is when the hugetlb memory is unreserved, we alsouncharge the file_region->reservation_counter.[akpm@linux-foundation.org: forward declare struct file_region]Signed-off-by: Mina Almasry Signed-off-by: Andrew Morton Reviewed-by: Mike Kravetz Cc: David Rientjes Cc: Greg Thelen Cc: Mike Kravetz Cc: Sandipan Das Cc: Shakeel Butt Cc: Shuah Khan Link: http://lkml.kernel.org/r/20200211213128.73302-5-almasrymina@google.comSigned-off-by: Linus Torvalds List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

e9fe92ae - hugetlb_cgroup: add reservation accounting for private mappings

Thu, 02 Apr 2020 04:11:21 +0000

hugetlb_cgroup: add reservation accounting for private mappingsNormally the pointer to the cgroup to uncharge hangs off the struct page,and gets queried when it's time to free the page. With hugetlb_cgroupreservations, this is not possible. Because it's possible for a page tobe reserved by one task and actually faulted in by another task.The best place to put the hugetlb_cgroup pointer to uncharge forreservations is in the resv_map. But, because the resv_map has differentsemantics for private and shared mappings, the code patch tocharge/uncharge shared and private mappings is different. This patchimplements charging and uncharging for private mappings.For private mappings, the counter to uncharge is inresv_map->reservation_counter. On initializing the resv_map this is setto NULL. On reservation of a region in private mapping, the taskshugetlb_cgroup is charged and the hugetlb_cgroup is placed isresv_map->reservation_counter.On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter.[akpm@linux-foundation.org: forward declare struct resv_map]Signed-off-by: Mina Almasry Signed-off-by: Andrew Morton Reviewed-by: Mike Kravetz Acked-by: David Rientjes Cc: Greg Thelen Cc: Sandipan Das Cc: Shakeel Butt Cc: Shuah Khan Link: http://lkml.kernel.org/r/20200211213128.73302-3-almasrymina@google.comSigned-off-by: Linus Torvalds List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

1adc4d41 - hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations

Thu, 02 Apr 2020 04:11:15 +0000

hugetlb_cgroup: add interface for charge/uncharge hugetlb reservationsAugments hugetlb_cgroup_charge_cgroup to be able to charge hugetlb usageor hugetlb reservation counter.Adds a new interface to uncharge a hugetlb_cgroup counter viahugetlb_cgroup_uncharge_counter.Integrates the counter with hugetlb_cgroup, via hugetlb_cgroup_init,hugetlb_cgroup_have_usage, and hugetlb_cgroup_css_offline.Signed-off-by: Mina Almasry Signed-off-by: Andrew Morton Acked-by: Mike Kravetz Acked-by: David Rientjes Cc: Greg Thelen Cc: Sandipan Das Cc: Shakeel Butt Cc: Shuah Khan Link: http://lkml.kernel.org/r/20200211213128.73302-2-almasrymina@google.comSigned-off-by: Linus Torvalds List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

7fab358d - include/linux/hugetlb*.h: clean up code

Fri, 20 May 2016 23:57:59 +0000

include/linux/hugetlb*.h: clean up codeMacro HUGETLBFS_SB is clear enough, so one statement is clearer than 3lines statements.Remove redundant return statements for non-return functions, which cansave lines, at least.Signed-off-by: Chen Gang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

1d798ca3 - mm: make compound_head() robust

Sat, 07 Nov 2015 00:29:54 +0000

mm: make compound_head() robustHugh has pointed that compound_head() call can be unsafe in somecontext. There's one example: CPU0 CPU1isolate_migratepages_block() page_count() compound_head() !!PageTail() == true put_page() tail->first_page = NULL head = tail->first_page alloc_pages(__GFP_COMP) prep_compound_page() tail->first_page = head __SetPageTail(p); !!PageTail() == true The race is pure theoretical. I don't it's possible to trigger it inpractice. But who knows.We can fix the race by changing how encode PageTail() and compound_head()within struct page to be able to update them in one shot.The patch introduces page->compound_head into third double word block infront of compound_dtor and compound_order. Bit 0 encodes PageTail() andthe rest bits are pointer to head page if bit zero is set.The patch moves page->pmd_huge_pte out of word, just in case if anarchitecture defines pgtable_t into something what can have the bit 0set.hugetlb_cgroup uses page->lru.next in the second tail page to storepointer struct hugetlb_cgroup. The patch switch it to use page->privatein the second tail page instead. The space is free since ->first_page isremoved from the union.The patch also opens possibility to remove HUGETLB_CGROUP_MIN_ORDERlimitation, since there's now space in first tail page to store structhugetlb_cgroup pointer. But that's out of scope of the patch.That means page->compound_head shares storage space with: - page->lru.next; - page->next; - page->rcu_head.next;That's too long list to be absolutely sure, but looks like nobody usesbit 0 of the word.page->rcu_head.next guaranteed[1] to have bit 0 clean as long as we usecall_rcu(), call_rcu_bh(), call_rcu_sched(), or call_srcu(). But futurecall_rcu_lazy() is not allowed as it makes use of the bit and we canget false positive PageTail().[1] http://lkml.kernel.org/g/20150827163634.GD4029@linux.vnet.ibm.comSigned-off-by: Kirill A. Shutemov Acked-by: Michal Hocko Reviewed-by: Andrea Arcangeli Cc: Hugh Dickins Cc: David Rientjes Cc: Vlastimil Babka Acked-by: Paul E. McKenney Cc: Aneesh Kumar K.V Cc: Andi Kleen Cc: Christoph Lameter Cc: Joonsoo Kim Cc: Sergey Senozhatsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/include/linux/hugetlb_cgroup.h

fc5ed1e9 - cgroup: replace cgroup_subsys->disabled tests with cgroup_subsys_enabled()

Fri, 18 Sep 2015 15:56:28 +0000

cgroup: replace cgroup_subsys->disabled tests with cgroup_subsys_enabled()Replace cgroup_subsys->disabled tests in controllers withcgroup_subsys_enabled(). cgroup_subsys_enabled() requires literalsubsys name as its parameter and thus can't be used for cgroup corewhich iterates through controllers. For cgroup core, introduce anduse cgroup_ssid_enabled() which uses slower static_key_enabled() testand can be indexed by subsys ID.This leaves cgroup_subsys->disabled unused. Removed.Signed-off-by: Tejun Heo Acked-by: Zefan Li Cc: Johannes Weiner Cc: Michal Hocko List of files: /linux-6.15/include/linux/hugetlb_cgroup.h