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[2003:d8:2f30:b00:cea9:dee:d607:41d]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-429dc1fda36sm11649953f8f.40.2025.11.05.09.51.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 05 Nov 2025 09:51:02 -0800 (PST) Message-ID: <021e8194-14bc-437a-a4ed-5e6abffb9827@redhat.com> Date: Wed, 5 Nov 2025 18:51:01 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/3] Revert "mm/ksm: convert break_ksm() from walk_page_range_vma() to folio_walk" To: Pedro Demarchi Gomes , Andrew Morton Cc: Xu Xin , Chengming Zhou , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20251105172756.167009-1-pedrodemargomes@gmail.com> <20251105172756.167009-2-pedrodemargomes@gmail.com> From: David Hildenbrand Content-Language: en-US In-Reply-To: <20251105172756.167009-2-pedrodemargomes@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 05.11.25 18:27, Pedro Demarchi Gomes wrote: > This reverts commit e317a8d8b4f600fc7ec9725e26417030ee594f52 and changes > function break_ksm_pmd_entry() to use folios. > > This reverts break_ksm() to use walk_page_range_vma() instead of > folio_walk_start(). > Change break_ksm_pmd_entry() to call is_ksm_zero_pte() only if we know > the folio is present, and also rename variable ret to found. > This will make it easier to later modify break_ksm() to perform a proper > range walk. > > Suggested-by: David Hildenbrand > Signed-off-by: Pedro Demarchi Gomes > --- > mm/ksm.c | 64 ++++++++++++++++++++++++++++++++++++++++++-------------- > 1 file changed, 48 insertions(+), 16 deletions(-) > > diff --git a/mm/ksm.c b/mm/ksm.c > index 4f672f4f2140..de10ebcf3509 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -607,6 +607,48 @@ static inline bool ksm_test_exit(struct mm_struct *mm) > return atomic_read(&mm->mm_users) == 0; > } > > +static int break_ksm_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long next, > + struct mm_walk *walk) > +{ > + struct folio *folio = NULL; > + spinlock_t *ptl; > + pte_t *pte; > + pte_t ptent; > + int found; > + > + pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); > + if (!pte) > + return 0; > + ptent = ptep_get(pte); > + if (pte_present(ptent)) { > + folio = vm_normal_folio(walk->vma, addr, ptent); > + } else if (!pte_none(ptent)) { > + swp_entry_t entry = pte_to_swp_entry(ptent); > + > + /* > + * As KSM pages remain KSM pages until freed, no need to wait > + * here for migration to end. > + */ > + if (is_migration_entry(entry)) > + folio = pfn_swap_entry_folio(entry); > + } > + /* return 1 if the page is an normal ksm page or KSM-placed zero page */ > + found = (folio && folio_test_ksm(folio)) || (pte_present(ptent) > + && is_ksm_zero_pte(ptent)); Nit: found = (folio && folio_test_ksm(folio)) || (pte_present(ptent)&& is_ksm_zero_pte(ptent)); Thanks! Acked-by: David Hildenbrand (Red Hat) -- Cheers David