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G3AUkGWI/L+l//po1uA6ZSBW0VQ6CrmD5Bx6WyW2XeuU4Nj+uQkp+B5Wv1RDcsP+Xo2ljSFVjde0g4/HPLviP2kAFwUWmNrYIhCZ36j8yltD9uK/TNoL53KcJbm9EAl+pfgOEKSt/XYzsqBEIXuAf7QGsYqmdjiz93B6XXZV63nhwp3heATRWt/KoSKCdcY8+m9Mk3uFDu76++oSs73fHEfRwr0GBgp1fila8OFeeWu2Ysrzhex1ePeV5ohU0h4yvkp3b071OaKtuzqoTDPKwlD0y6i9eFyrHODZm6O71MMnKMXwfjqV+zxCWXJfiR8oaGicgzexZnWY3XzXunqo/nm7H/vhc5Gkr3/UmFTdsYowxL2frjxHFlvfuJjL9QKOhKBkGhRLXCCJLmv6iTjFIeCGhWFCdyGOvfTZICUSEIlfIx563NqXKE8erpg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 27 Feb 2025, at 10:14, Matthew Wilcox wrote: > On Thu, Feb 27, 2025 at 05:55:43AM +0000, Matthew Wilcox wrote: >> On Wed, Feb 26, 2025 at 04:00:25PM -0500, Zi Yan wrote: >>> +static int __split_unmapped_folio(struct folio *folio, int new_order, >>> + struct page *split_at, struct page *lock_at, >>> + struct list_head *list, pgoff_t end, >>> + struct xa_state *xas, struct address_space *mapping, >>> + bool uniform_split) >>> +{ >> [...] >>> + /* complete memcg works before add pages to LRU */ >>> + split_page_memcg(&folio->page, old_order, split_order); >>> + split_page_owner(&folio->page, old_order, split_order); >>> + pgalloc_tag_split(folio, old_order, split_order); >> >> At least split_page_memcg() needs to become aware of 'uniform_split'. >> >> if (folio_memcg_kmem(folio)) >> obj_cgroup_get_many(__folio_objcg(folio), old_nr / new_n= r - 1); >> >> If we're doing uniform_split, that calculation should be >> old_order - new_order - 1 > > umm, old_order - new_order. Anyway, here's a patch I've done on top of > your work, but it probably needs to be massaged slightly and placed > before your work? Wait. uniform_split is the existing splitting one order-9 to 512 order-0 approach, so split_page_memcg() still works. For !uniform_split, split_page_memcg() is called multiple times, each time old_order =3D new_order + 1, so what split_page_memcg() does is: 1. two order-8 folios get their memcg, and ref count is increased by 1; 2. one of the order-8s is split into two order-7, each of which gets their memcg, and ref count is increased by 1; =E2=80=A6 8. one of the order-1s is split into two order-0, each of which gets their memcg, and ref count is increased by 1. At the end, the refcount is increased by old_order - new_order like you described above. Let me know if it makes sense to you. > > From 190e13ed77e562eb59fa1fa4bfefdefe5d0416ed Mon Sep 17 00:00:00 2001 > From: "Matthew Wilcox (Oracle)" > Date: Mon, 28 Oct 2024 16:23:30 -0400 > Subject: [PATCH] mm: Separate folio_split_memcg() from split_page_memcg() > > Folios always use memcg_data to refer to the mem_cgroup while pages > allocated with GFP_ACCOUNT have a pointer to the obj_cgroup. Since the > caller already knows what it has, split the function into two and then > we don't need to check. > > Signed-off-by: Matthew Wilcox (Oracle) > --- > include/linux/memcontrol.h | 7 +++++++ > mm/huge_memory.c | 6 ++++-- > mm/memcontrol.c | 18 +++++++++++++++--- > 3 files changed, 26 insertions(+), 5 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 57664e2a8fb7..155c3f81f4df 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -1039,6 +1039,8 @@ static inline void memcg_memory_event_mm(struct mm_= struct *mm, > } > > void split_page_memcg(struct page *head, int old_order, int new_order); > +void folio_split_memcg(struct folio *folio, unsigned old_order, > + unsigned new_order, bool uniform_split); > > static inline u64 cgroup_id_from_mm(struct mm_struct *mm) > { > @@ -1463,6 +1465,11 @@ static inline void split_page_memcg(struct page *h= ead, int old_order, int new_or > { > } > > +static inline void folio_split_memcg(struct folio *folio, unsigned old_o= rder, > + unsigned new_order, bool uniform) > +{ > +} > + > static inline u64 cgroup_id_from_mm(struct mm_struct *mm) > { > return 0; > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 1e45064046a0..75fa9c9d9ec9 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -3401,6 +3401,9 @@ static void __split_folio_to_order(struct folio *fo= lio, int new_order) > folio_set_young(new_folio); > if (folio_test_idle(folio)) > folio_set_idle(new_folio); > +#ifdef CONFIG_MEMCG > + new_folio->memcg_data =3D folio->memcg_data; > +#endif > > folio_xchg_last_cpupid(new_folio, folio_last_cpupid(folio)); > } > @@ -3529,8 +3532,7 @@ static int __split_unmapped_folio(struct folio *fol= io, int new_order, > } > } > > - /* complete memcg works before add pages to LRU */ > - split_page_memcg(&folio->page, old_order, split_order); > + folio_split_memcg(folio, old_order, split_order, uniform_split); > split_page_owner(&folio->page, old_order, split_order); > pgalloc_tag_split(folio, old_order, split_order); > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 16f3bdbd37d8..c2d41e1337cb 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -3064,10 +3064,22 @@ void split_page_memcg(struct page *head, int old_= order, int new_order) > for (i =3D new_nr; i < old_nr; i +=3D new_nr) > folio_page(folio, i)->memcg_data =3D folio->memcg_data; > > - if (folio_memcg_kmem(folio)) > - obj_cgroup_get_many(__folio_objcg(folio), old_nr / new_nr - 1); > + obj_cgroup_get_many(__folio_objcg(folio), old_nr / new_nr - 1); > +} > + > +void folio_split_memcg(struct folio *folio, unsigned old_order, > + unsigned new_order, bool uniform_split) > +{ > + unsigned new_refs; > + > + if (mem_cgroup_disabled() || !folio_memcg_charged(folio)) > + return; > + > + if (uniform_split) > + new_refs =3D (1 << (old_order - new_order)) - 1; > else > - css_get_many(&folio_memcg(folio)->css, old_nr / new_nr - 1); > + new_refs =3D old_order - new_order; > + css_get_many(&__folio_memcg(folio)->css, new_refs); > } > > unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) > --=20 > 2.47.2 Best Regards, Yan, Zi