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b=YlegRbPyfJSaVVQWD97w0tpENa8G1akqMLmPiaL64UEUdemubV5zjP+0EfGoV456w Uifzj7cb+vqbQ9XV9k0NZuiHdjgq2bbtktteEEZCqU+RyfE8Vdzs14C6QjTn3dk6ex QG9bT67uVMzA8K/x0tiPCTdfiCFFlBRhlNL9GZTklh54hroAlXxqi4bnRFWMbo4R6R /EkSIQ99nHp7NsW3bNj1lcbStY08CYCKLK3E/QiLT/9dA1F/p/qi+HC4F9ZCa+i/hK GMYVXvajUrnN01mEg2OK5Ej+gpXbBw0EoN3rLbOAA1buCrlaLRELjpJxcKrpZI/XcI 0K2+nD7J24Zuw== Date: Wed, 23 Sep 2026 17:00:41 +0100 From: "Lorenzo Stoakes (ARM)" To: Gregory Price Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-team@meta.com, akpm@linux-foundation.org, liam@infradead.org, david@kernel.org, vbabka@kernel.org, jannh@google.com, rppt@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org Subject: Re: [PATCH 03/10] mm/madvise: factor shared LRU folio handling Message-ID: References: <20260922235830.2350770-1-gourry@gourry.net> <20260922235830.2350770-4-gourry@gourry.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260922235830.2350770-4-gourry@gourry.net> X-Rspam-User: X-Stat-Signature: wd7bp59ars3udfzutsrq4ubn88enay5u X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C751320017 X-HE-Tag: 1790179247-596060 X-HE-Meta: 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 ApgXMLQc C/NkN/UaOUUtBkfh3D5751dtuo9MNFkQ98C/Ksel+kWG0RODUyM82Q2h+kz1SX3LpYqSlxuAh9YhV/8zB2x4g0GTj0bi/yzH2E+/O+86/EKXBEOTn+pmjBNJka8P1yjvS1xhq9VDK02t9EQxC4ck5yzNemoEcxzhYEIhZhms9w0h9+qFnfPmQ/FdvInaF6Ss9kN+jG7F+mcgDev84Gf3JkJ4Lr9v7dEQYlfeTBd61QWSYDLSrBC6Yc1fL3x9YRFTwDQwxb1KfWz1sjcUZcLef+sR2BxTjb0ztMng+pKMu1qc2wzLrt1+/1DYYRB3XABI3sJzXXDH4r7S56SuErVUbHs+S0w== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 22, 2026 at 07:58:23PM -0400, Gregory Price wrote: > The huge-PMD and PTE paths duplicate folio filtering, reference clearing, > deactivation and pageout isolation. Keeping both copies synchronized > obscures the page-table-specific control flow. > > Factor the common filtering and LRU operation into helpers. Keep the > lock-before-reference sequence visible at each split site because an early > reference can prevent split_folio() from succeeding. > > No functional change intended. > > Assisted-by: LLM > Signed-off-by: Gregory Price (Meta) LGTM and AFAICT all the code is the same as before just less horrifying so: Reviewed-by: Lorenzo Stoakes (ARM) > --- > mm/madvise.c | 90 +++++++++++++++++++++++++--------------------------- > 1 file changed, 43 insertions(+), 47 deletions(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 83d54ab385da8..c345fef23f15d 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -361,6 +361,39 @@ static inline int madvise_folio_pte_batch(unsigned long addr, unsigned long end, > FPB_MERGE_YOUNG_DIRTY); > } > > +static inline void > +madvise_lru_folio(struct folio *folio, bool pageout, > + struct list_head *folio_list) > +{ > + /* > + * Clear references before deactivating or reclaiming the folio. This can > + * make idle-page tracking miss recent accesses. > + */ > + folio_clear_referenced(folio); > + folio_test_clear_young(folio); > + if (folio_test_active(folio)) > + folio_set_workingset(folio); > + > + if (!pageout) { > + folio_deactivate(folio); > + return; > + } > + > + if (!folio_isolate_lru(folio)) > + return; > + if (folio_test_unevictable(folio)) > + folio_putback_lru(folio); > + else > + list_add(&folio->lru, folio_list); > +} > + > +static bool madvise_lru_folio_is_filtered(struct folio *folio, > + bool pageout_anon_only) > +{ > + return folio_maybe_mapped_shared(folio) || > + (pageout_anon_only && !folio_test_anon(folio)); > +} > + > static int madvise_lru_pmd_entry(pmd_t *pmd, unsigned long addr, > unsigned long end, struct mm_walk *walk) > { > @@ -373,15 +406,14 @@ static int madvise_lru_pmd_entry(pmd_t *pmd, unsigned long addr, > spinlock_t *ptl; > struct folio *folio = NULL; > LIST_HEAD(folio_list); > - bool pageout_anon_only_filter; > unsigned int batch_count = 0; > + bool pageout_anon_only; > int nr; > > if (fatal_signal_pending(current)) > return -EINTR; > - > - pageout_anon_only_filter = pageout && !vma_is_anonymous(vma) && > - !can_do_file_pageout(vma); > + pageout_anon_only = pageout && !vma_is_anonymous(vma) && > + !can_do_file_pageout(vma); > > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > if (pmd_trans_huge(*pmd)) { > @@ -407,11 +439,7 @@ static int madvise_lru_pmd_entry(pmd_t *pmd, unsigned long addr, > if (folio_is_zone_device(folio)) > goto huge_unlock; > > - /* Do not interfere with other mappings of this folio */ > - if (folio_maybe_mapped_shared(folio)) > - goto huge_unlock; > - > - if (pageout_anon_only_filter && !folio_test_anon(folio)) > + if (madvise_lru_folio_is_filtered(folio, pageout_anon_only)) > goto huge_unlock; > > if (next - addr != HPAGE_PMD_SIZE) { > @@ -437,19 +465,7 @@ static int madvise_lru_pmd_entry(pmd_t *pmd, unsigned long addr, > tlb_remove_pmd_tlb_entry(tlb, pmd, addr); > } > > - folio_clear_referenced(folio); > - folio_test_clear_young(folio); > - if (folio_test_active(folio)) > - folio_set_workingset(folio); > - if (pageout) { > - if (folio_isolate_lru(folio)) { > - if (folio_test_unevictable(folio)) > - folio_putback_lru(folio); > - else > - list_add(&folio->lru, &folio_list); > - } > - } else > - folio_deactivate(folio); > + madvise_lru_folio(folio, pageout, &folio_list); > huge_unlock: > spin_unlock(ptl); > if (pageout) > @@ -502,9 +518,7 @@ static int madvise_lru_pmd_entry(pmd_t *pmd, unsigned long addr, > if (nr < folio_nr_pages(folio)) { > int err; > > - if (folio_maybe_mapped_shared(folio)) > - continue; > - if (pageout_anon_only_filter && !folio_test_anon(folio)) > + if (madvise_lru_folio_is_filtered(folio, pageout_anon_only)) > continue; > if (!folio_trylock(folio)) > continue; > @@ -537,7 +551,7 @@ static int madvise_lru_pmd_entry(pmd_t *pmd, unsigned long addr, > folio_mapcount(folio) != folio_nr_pages(folio)) > continue; > > - if (pageout_anon_only_filter && !folio_test_anon(folio)) > + if (pageout_anon_only && !folio_test_anon(folio)) > continue; > > if (!pageout && pte_young(ptent)) { > @@ -546,25 +560,7 @@ static int madvise_lru_pmd_entry(pmd_t *pmd, unsigned long addr, > tlb_remove_tlb_entries(tlb, pte, nr, addr); > } > > - /* > - * We are deactivating a folio for accelerating reclaiming. > - * VM couldn't reclaim the folio unless we clear PG_young. > - * As a side effect, it makes confuse idle-page tracking > - * because they will miss recent referenced history. > - */ > - folio_clear_referenced(folio); > - folio_test_clear_young(folio); > - if (folio_test_active(folio)) > - folio_set_workingset(folio); > - if (pageout) { > - if (folio_isolate_lru(folio)) { > - if (folio_test_unevictable(folio)) > - folio_putback_lru(folio); > - else > - list_add(&folio->lru, &folio_list); > - } > - } else > - folio_deactivate(folio); > + madvise_lru_folio(folio, pageout, &folio_list); > } > > out: > @@ -651,8 +647,8 @@ static long madvise_pageout(struct madvise_behavior *madv_behavior) > * owner nor write capable of the file. We allow private file mappings > * further to pageout dirty anon pages. > */ > - if (!vma_is_anonymous(vma) && (!can_do_file_pageout(vma) && > - (vma->vm_flags & VM_MAYSHARE))) > + if (!vma_is_anonymous(vma) && !can_do_file_pageout(vma) && > + (vma->vm_flags & VM_MAYSHARE)) > return 0; > > lru_add_drain(); > -- > 2.53.0-Meta > -- Cheers, Lorenzo