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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776987501; bh=m87qmd7Z7VaIUVFoNxdf2avdmQw/zQ+LpBXrHU3kp3k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ur5+oKf5omajvu4YTf4FQLfJpFR7xWxwrKvdnuS6jTpwApmMfG/zUCz7pTF1gdkHq EDd3QWmhLxHPGclw5caWcxpq8S9oZC003AqYOb4pj8tDoNiVotVcyaMxyd01Y/+BWH vpykZTPIqeo5syvHkBnrgJtvqVImkYnH/H4ZXw33xkch4F9Af+N1wVRk5EidtAwXPl cvEojTI8NOTZzK4UFmVPpkNUpjcJd7uLcZkSR9KcP0ECZdrfyGontr+eA0W+0LCs+G ouvortnDt7jiSXxzb8F8NcPgzaYJ4hc1RkSXuRsqmKE2uR0hqm9+fBy2q61lqiZqXE rjjeh4jG8sOcA== Date: Thu, 23 Apr 2026 16:38:19 -0700 From: Minchan Kim To: Baolin Wang Cc: akpm@linux-foundation.org, hca@linux.ibm.com, linux-s390@vger.kernel.org, david@kernel.org, mhocko@suse.com, brauner@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, surenb@google.com, timmurray@google.com Subject: Re: [PATCH v1 2/3] mm: process_mrelease: skip LRU movement for exclusive file folios Message-ID: References: <20260421230239.172582-1-minchan@kernel.org> <20260421230239.172582-3-minchan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: C0A6C1C0002 X-Rspamd-Server: rspam12 X-Stat-Signature: 1ce57gn8rgoaxr3hjqcjjft3188ke9fu X-Rspam-User: X-HE-Tag: 1776987502-23964 X-HE-Meta: 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 iAL3A81y 0f0Eyinerbg0qkWhyZ+xzC1BfolPgT/BIYPbzUYjBFvqFzzE0D7hWFIMls3n99u6hu/+C+WWQGAg9sKjNmYsSqaeqlNRpGXk6m/bzHFAjS/K4YZm5mvQvCShGwqAjS0BhwAvZg7xAIbqwvrG3xvrn4eWP6Rcd7yUD+eDNHiWYkAt+TIqRuit7OFRjx29WzatIzNOmeWfLkj31buVUUbjaS8tUkiny2QD4vDnhN2oeuAWxA7QDwvDoBsXfYkbkrnUGhW0ZB/svq7nbA1fCLU8wEinQgnuJWPhxh+FYQ+4Im9wnBSOeLFelhSFVIPPf9tUA1CYm Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Apr 22, 2026 at 03:22:46PM +0800, Baolin Wang wrote: > > > On 4/22/26 7:02 AM, Minchan Kim wrote: > > For the process_mrelease reclaim, skip LRU handling for exclusive > > file-backed folios since they will be freed soon so pointless > > to move around in the LRU. > > > > This avoids costly LRU movement which accounts for a significant portion > > of the time during unmap_page_range. > > > > - 91.31% 0.00% mmap_exit_test [kernel.kallsyms] [.] exit_mm > > exit_mm > > __mmput > > exit_mmap > > unmap_vmas > > - unmap_page_range > > - 55.75% folio_mark_accessed > > + 48.79% __folio_batch_add_and_move > > 4.23% workingset_activation > > + 12.94% folio_remove_rmap_ptes > > + 9.86% page_table_check_clear > > + 3.34% tlb_flush_mmu > > 1.06% __page_table_check_pte_clear > > > > Signed-off-by: Minchan Kim > > --- > > mm/memory.c | 13 ++++++++++++- > > 1 file changed, 12 insertions(+), 1 deletion(-) > > > > diff --git a/mm/memory.c b/mm/memory.c > > index 2f815a34d924..fcb57630bb8d 100644 > > --- a/mm/memory.c > > +++ b/mm/memory.c > > @@ -1640,6 +1640,8 @@ static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb, > > bool delay_rmap = false; > > if (!folio_test_anon(folio)) { > > + bool skip_mark_accessed; > > + > > ptent = get_and_clear_full_ptes(mm, addr, pte, nr, tlb->fullmm); > > if (pte_dirty(ptent)) { > > folio_mark_dirty(folio); > > @@ -1648,7 +1650,16 @@ static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb, > > *force_flush = true; > > } > > } > > - if (pte_young(ptent) && likely(vma_has_recency(vma))) > > + > > + /* > > + * For the process_mrelease reclaim, skip LRU handling for exclusive > > + * file-backed folios since they will be freed soon so pointless > > + * to move around in the LRU. > > + */ > > + skip_mark_accessed = mm_flags_test(MMF_UNSTABLE, mm) && > > + !folio_maybe_mapped_shared(folio); > > + if (likely(!skip_mark_accessed) && pte_young(ptent) && > > + likely(vma_has_recency(vma))) > > folio_mark_accessed(folio); > > rss[mm_counter(folio)] -= nr; > > } else { > > Seems we should also skip marking exclusive pmd-sized folios as accessed in > zap_huge_pmd_folio(). Good catch. Will update in next revision. Thank you.