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b=JO/jWyeJufM2+qQ2uYQR3y6n98G0GbZQkqz5wB0k6OWIbVAHSwjhbayHwfCnIrgAy M2+EDF3akJCH0EV5UTAw8vlRacxAfOszop2EZ188qZgRikeFtkEJB7XDUZyGaqWFv1 dr9+3zsBxuZItswx51Eb7fmsj3hbEImbajbLeoO0ZQF55g6/QfrduIE8bnwd56yQHR yz9M+0T47jxUJ+8eGqED2QyfHearGh/6DgdNQsPRZgGn9OARfEJwMYHFYDeqvdtQbe +MMW4xroo4a8LlP0+nkxWqyN7JV3FgB/Ra5KOdMVyqG5gcMLKzkcjky+q5h4bMACB+ l1nVY74IllSNg== Message-ID: Date: Mon, 27 Apr 2026 11:29:14 +0200 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 Cc: akpm@linux-foundation.org, 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 References: <20260421230239.172582-1-minchan@kernel.org> <20260421230239.172582-2-minchan@kernel.org> <7b4bf980-4ff3-4f53-8c64-1ba2d85cf1b8@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 X-Rspam-User: X-Rspamd-Queue-Id: 44EBB2000E X-Rspamd-Server: rspam04 X-Stat-Signature: ontp1w7nezj5n7ooeih39beipthpak47 X-HE-Tag: 1777282161-203169 X-HE-Meta: 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 L4oq89mK qcorAp2DR/t/go2wck3cgVWtjFS3Pau8nyLRTC1zMEKejTkMVqvHwncJKclsAkqjYWDWfAnMlicuKN1GJ7bPIr0+zsesr4xfVnoKFw/1sLoMJSQCAbgVq2rkTkDkL65vMr79Px5s1U1xrBPu/OaEzN3LXJki2e8iNwmEmMPBWUkXkMPNft8HOJxPQsQVwte7f80hMX4vy93CW2T/P8Kfavtnoq9U3fzwLYwRrRrkY+tS8NRY2tF4vEZnsjrqXZsrYpS4p+MGT/RIkQGCb4iGsZdXRbFH3kTP+7CzeZgMZf4ojP8jWI66NFmfCRJYgmIiwGX9kjYI4R6JJIZfsGxfWTC2Ch34v71Fhaoc15Lm9WPz/3n4= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/24/26 23:24, Minchan Kim wrote: > On Fri, Apr 24, 2026 at 09:56:01AM +0200, David Hildenbrand (Arm) wrote: >> 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. > > Makes sense. > >> >> Also, is there a way to avoid moving the function? > > I guess you are talking about "free_pages_and_swap_cache". > > The problem is mm/swap_state.c is conditionally compiled only when CONFIG_SWAP > is enabled. > > Since the expedited clean file cache eviction should be available > even on !CONFIG_SWAP, we need this function to be compiled unconditionally. > That is why I moved it to swap.c, which is always compiled. Ah, right. Please spell that out in the patch description! -- Cheers, David