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 661E634A788; Fri, 24 Apr 2026 07:56:07 +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=1777017367; cv=none; b=un4wKtHsFpQOvTFS7RCwX6l4Bv6RHDzLxD2291/ENoy7/qUOAuYIw7tJTy9aXFsimslEAbvaUq/KORZgROQN6czvsNceYHt39+1+i7sb6FQu6sirVmpSg4DO8sE5/FcImAQgX7LNkdjyYUkHaZ7rZT+1osueAKUzmsW4dl+W4Hs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777017367; c=relaxed/simple; bh=cOX51pLs474pi005MOfvb17akqyNW7MI+y9gkwPe5rA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=VmOYMmTmghn8+tL2eyd8StOXxapW7Kl5I4NGiWHiZmt47UOPeauvYhAMqAp5kdSKq2KI0ucXtDMDnGt+t+4dPRIo0wls9jkON8LrSZwSPwo1BMa9JCBNTXUIz2P/imDfcZJQijW6G4uMp9BM66iNPfSK4xeXT5h4X3HPjADGIHo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pjktQOmh; 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="pjktQOmh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8F72EC19425; Fri, 24 Apr 2026 07:56:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777017367; bh=cOX51pLs474pi005MOfvb17akqyNW7MI+y9gkwPe5rA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pjktQOmhx/sH0iMOwAA99wAlDyOT8OQNlWORxK6FjzzP/ORvSr1hXOhn/+yMLq389 w4khR5Rkb8j6ka5PZIyTIPS1N+f1fvek3m1RjZUdWCQiGm5Ir402sn5Fqqil6w18pN w0olg0p0PmWPcetDUap1kdx1dQ2ioLKKLQwp93a5J1z9rKEPcqtgs5PeTLm6VcPbi9 hNAh61GkRKILlus9vFvTlsXytTjwZoRhnSuwSM8r8FGl0K86MUah83xIoO93DvTiA+ QD2Oldk8qpEvdGjQvphvV6jBNtYy5P7GuwvVvyrkhTPDbcmxY5J3ruM2C6xAYyLsNN 2zD7l6+rbC6Eg== Message-ID: <7b4bf980-4ff3-4f53-8c64-1ba2d85cf1b8@kernel.org> Date: Fri, 24 Apr 2026 09:56:01 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/3] mm: process_mrelease: expedite clean file folio reclaim via mmu_gather To: Minchan Kim , akpm@linux-foundation.org Cc: hca@linux.ibm.com, linux-s390@vger.kernel.org, mhocko@suse.com, brauner@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, surenb@google.com, timmurray@google.com, Minchan Kim References: <20260421230239.172582-1-minchan@kernel.org> <20260421230239.172582-2-minchan@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/22/26 01:02, Minchan Kim wrote: Can we make the subject easier to understand? "mm: process_mrelease: evict clean file folios when reaping a process" > 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. There is no such parameter. But I do wonder if such a parameter would be better than passing in the MM here. Also, is there a way to avoid moving the function? -- Cheers, David