From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1305C313E1D; Fri, 8 May 2026 21:56:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778277397; cv=none; b=iPQMsPMneSRb2+LpXrSWTeQkwjMhyN5zCcydSHNUl2saZeX1T6jyEWDfYSU49LqXtBbKOSDUGlN6Fi3OK0G+I+jNwrIaErYwvXczyityHDhRvTS8eN+ppp6Qk5Xi0WD7ukNHup/7GL8xp5kp5+dfsgEfZl9LinO5Htvvxs+L/Q0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778277397; c=relaxed/simple; bh=E4/S7h7x9+VkHjz+trqpUCCjAbfa/5Fb4fkF5zP2WWo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WHdKRXzTx5tbojZG2l5VjnnZ7S1MGCouAYDeveQwfDAb+gwiRv0tj2pF9PFax9qpewUhdHTz7jB4ixZHsjCHnHIDFxGERAvrUuPzFhFJ+KEqk26M4Pdkrf9Wt9dIoC32IFjFCyu69nTN3G57CD5tC13puj6huVGqxkecsBH438w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gjLk8Q+i; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gjLk8Q+i" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C1BDC2BCB0; Fri, 8 May 2026 21:56:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778277396; bh=E4/S7h7x9+VkHjz+trqpUCCjAbfa/5Fb4fkF5zP2WWo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gjLk8Q+iHwQyjywvpCvrlThddaPjfA0/KW7CRqpZtRFNbAGzgwUw/Tn732VkbmWeF JZgyUs6HKHSY6uy8MeTO51AZ+LiqFjo3qnmlggQLR1PqYvMSTjVEAGrpaJjf1VY6g3 VRAG2yKL93gQiRku2ORPFgMG/QupHaHQUeNB4xlxQ5kom9kRfpvyq30QyzQD5kxrHI D+uFnS/Ys0/RglApXgB67b0ip6zGJoWuJVlpMxJTZ6U7NKjtZvb4s8kob30r7ip6zM aJ7Xsq34gCpUimFZK1VY97zJUmyGJPKXgaXkXtXfsZPbdHHOjaVyJ0BmJa3S2L5F2X 5CGXGLyS1Oiqw== Date: Fri, 8 May 2026 14:56:35 -0700 From: Minchan Kim To: Alexander Gordeev 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 1/3] mm: process_mrelease: expedite clean file folio reclaim via mmu_gather Message-ID: References: <20260421230239.172582-1-minchan@kernel.org> <20260421230239.172582-2-minchan@kernel.org> <20260505145318.97692A14-agordeev@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260505145318.97692A14-agordeev@linux.ibm.com> Hi Alexander, Sorry for late reply. On Tue, May 05, 2026 at 04:53:18PM +0200, Alexander Gordeev wrote: > On Tue, Apr 21, 2026 at 04:02:37PM -0700, Minchan Kim wrote: > > Hi Minchan, > > > Currently, process_mrelease() unmaps pages but file-backed pages are > > not evicted and stay in the pagecache, relying on standard memory reclaim > > (kswapd or direct reclaim) to eventually free them. This delays the > > immediate recovery of system memory under Android's LMKD scenarios, > > leading to redundant background apps kills. > > > > This patch implements an expedited eviction mechanism for clean pagecache > > folios in the mmu_gather code, similar to how swapcache folios are handled. > > It drops them from the pagecache (i.e., evicting them) if they are completely > > unmapped during reaping. > > > > Within this single unified loop, anonymous pages are released via > > free_swap_cache(), and file-backed folios are symmetrically released via > > free_file_cache(). > > > > Signed-off-by: Minchan Kim > > --- > > arch/s390/include/asm/tlb.h | 2 +- > > include/linux/swap.h | 5 ++--- > > mm/mmu_gather.c | 7 ++++--- > > mm/swap.c | 42 +++++++++++++++++++++++++++++++++++++ > > mm/swap_state.c | 26 ----------------------- > > 5 files changed, 49 insertions(+), 33 deletions(-) > > > > diff --git a/arch/s390/include/asm/tlb.h b/arch/s390/include/asm/tlb.h > > index 619fd41e710e..2736dbb571a8 100644 > > --- a/arch/s390/include/asm/tlb.h > > +++ b/arch/s390/include/asm/tlb.h > > @@ -62,7 +62,7 @@ static inline bool __tlb_remove_folio_pages(struct mmu_gather *tlb, > > VM_WARN_ON_ONCE(delay_rmap); > > VM_WARN_ON_ONCE(page_folio(page) != page_folio(page + nr_pages - 1)); > > > > - free_pages_and_swap_cache(encoded_pages, ARRAY_SIZE(encoded_pages)); > > + free_pages_and_caches(tlb->mm, encoded_pages, ARRAY_SIZE(encoded_pages)); > > return false; > > } > > > > diff --git a/include/linux/swap.h b/include/linux/swap.h > > index 62fc7499b408..bdb784966343 100644 > > --- a/include/linux/swap.h > > +++ b/include/linux/swap.h > > @@ -414,7 +414,9 @@ extern int sysctl_min_unmapped_ratio; > > extern int sysctl_min_slab_ratio; > > #endif > > > > +struct mm_struct; > > void check_move_unevictable_folios(struct folio_batch *fbatch); > > +void free_pages_and_caches(struct mm_struct *mm, struct encoded_page **pages, int nr); > > > > extern void __meminit kswapd_run(int nid); > > extern void __meminit kswapd_stop(int nid); > > @@ -433,7 +435,6 @@ static inline unsigned long total_swapcache_pages(void) > > > > void free_swap_cache(struct folio *folio); > > void free_folio_and_swap_cache(struct folio *folio); > > -void free_pages_and_swap_cache(struct encoded_page **, int); > > /* linux/mm/swapfile.c */ > > extern atomic_long_t nr_swap_pages; > > extern long total_swap_pages; > > @@ -510,8 +511,6 @@ static inline void put_swap_device(struct swap_info_struct *si) > > do { (val)->freeswap = (val)->totalswap = 0; } while (0) > > #define free_folio_and_swap_cache(folio) \ > > folio_put(folio) > > -#define free_pages_and_swap_cache(pages, nr) \ > > - release_pages((pages), (nr)); > > > > static inline void free_swap_cache(struct folio *folio) > > { > > diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c > > index fe5b6a031717..3c6c315d3c48 100644 > > --- a/mm/mmu_gather.c > > +++ b/mm/mmu_gather.c > > @@ -100,7 +100,8 @@ void tlb_flush_rmaps(struct mmu_gather *tlb, struct vm_area_struct *vma) > > */ > > #define MAX_NR_FOLIOS_PER_FREE 512 > > > > -static void __tlb_batch_free_encoded_pages(struct mmu_gather_batch *batch) > > +static void __tlb_batch_free_encoded_pages(struct mm_struct *mm, > > + struct mmu_gather_batch *batch) > > { > > struct encoded_page **pages = batch->encoded_pages; > > unsigned int nr, nr_pages; > > @@ -135,7 +136,7 @@ static void __tlb_batch_free_encoded_pages(struct mmu_gather_batch *batch) > > } > > } > > > > - free_pages_and_swap_cache(pages, nr); > > + free_pages_and_caches(mm, pages, nr); > > pages += nr; > > batch->nr -= nr; > > > > @@ -148,7 +149,7 @@ static void tlb_batch_pages_flush(struct mmu_gather *tlb) > > struct mmu_gather_batch *batch; > > > > for (batch = &tlb->local; batch && batch->nr; batch = batch->next) > > - __tlb_batch_free_encoded_pages(batch); > > + __tlb_batch_free_encoded_pages(tlb->mm, batch); > > tlb->active = &tlb->local; > > } > > > > diff --git a/mm/swap.c b/mm/swap.c > > index bb19ccbece46..e44bc8cefceb 100644 > > --- a/mm/swap.c > > +++ b/mm/swap.c > > @@ -1043,6 +1043,48 @@ void release_pages(release_pages_arg arg, int nr) > > } > > EXPORT_SYMBOL(release_pages); > > > > +static inline void free_file_cache(struct folio *folio) > > +{ > > + if (folio_trylock(folio)) { > > + mapping_evict_folio(folio_mapping(folio), folio); > > + folio_unlock(folio); > > + } > > +} > > + > > +/* > > + * Passed an array of pages, drop them all from swapcache and then release > > + * them. They are removed from the LRU and freed if this is their last use. > > + * > > + * If @try_evict_file_folios is true, this function will proactively evict clean > > + * file-backed folios if they are no longer mapped. > > + */ > > +void free_pages_and_caches(struct mm_struct *mm, struct encoded_page **pages, int nr) > > +{ > > + bool try_evict_file_folios = mm_flags_test(MMF_UNSTABLE, mm); > > + struct folio_batch folios; > > + unsigned int refs[PAGEVEC_SIZE]; > > + > > + folio_batch_init(&folios); > > + for (int i = 0; i < nr; i++) { > > + struct folio *folio = page_folio(encoded_page_ptr(pages[i])); > > + > > + if (folio_test_anon(folio)) > > + free_swap_cache(folio); > > + else if (unlikely(try_evict_file_folios)) > > + free_file_cache(folio); > > This condition is absent in free_pages_and_swap_cache(). > What would happen with non-anon and non-evict folio? Are you asking about mlocked pages for file? During unmapping, munlock_vma_folio() inside __folio_remove_rmap() clears the PG_mlocked flag and moves the folio back to the evictable LRU list. By the time the folios reach free_pages_and_caches(), if the folio is exclusive, it will be successfully evicted. However, if the folio is shared, mapping_evict_folio() detects it via the refcount check and skips the eviction. However, I realized we miss shmem folios in the swap cache due to the new folio_test_anon() check we introduced. I will update the check to something like this: if (folio_test_swapcache(folio)) free_swap_cache(folio); else if (unlikely(try_evict_file_folios)) free_file_cache(folio); Let me know if I missed something from your point. Thank you.