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b=nVPtCIXX7qOBaSvM5QmkXUn3tYNPLBMCpG2MdFx9idi80eVvMbSGJwS+UcF+fnTT8 PWvGguUwpRyAiw9KBWeSbcf0EQhIWGQ2b0csXb2BhGk5UitWzfro1R3yhQ1b2tjzjM /V8gWATJuUNsIdMf9NXU8SeyuklajXCemBls29wmHZNfqyqcAn0nA1zJIJYsNWDKtC h2yOKy0XqPXCwRv5Zq/eP970iLQQHGaV+4bUE6fz17zx3FbtmbIraHOjaq4TEDuaXO nrimnLhiOVYJf9AGFMQWc8ksSieAtHpmTQ+4JufIOjoRXsXlBxLdE61+7vp4gWCbZw fA3ykw/jMytIg== Date: Mon, 27 Apr 2026 15:04:22 -0700 From: Minchan Kim To: "David Hildenbrand (Arm)" 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 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> <7b4bf980-4ff3-4f53-8c64-1ba2d85cf1b8@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Queue-Id: 8F1AD18000F X-Rspamd-Server: rspam04 X-Stat-Signature: zpbyyrt1aotse93dfzuc413s3q13czm5 X-HE-Tag: 1777327465-890140 X-HE-Meta: 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 ib9i9wwg JL2SEq3x9AEhGUUTQq398e76p7ICui/z0/lct4sBDvqWf3mqJRuZ2WoywmmksaS6C5FWoO+lARg1ojbfoVp2QXODd4QnE7kp8Z2bK3uYE8ClEdd01xrOKJyaSAkoTVkBnywtKZLK53QI+k87SPbZfklXShXJaISmif9Sv8IbdSk5txQwCaUGetR8pjFz1qWAOzVzfBjZ8EglAwNG/saxIs5XiK1vN4AtsgF2f7hQJ2+eEkXsYh7fG0po3FtDSZ7KT8M7FFXKrFkZF1YsygAGgUN9bfYV5qctoUOsHCc4S7x7mFWztXuJhuIwY4IKYSBgyBEH75MLIF23AfEn9crrXA+No1o2uCNqSk9Mx Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 27, 2026 at 11:29:14AM +0200, David Hildenbrand (Arm) wrote: > 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! Acked.