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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-5d762052af1sm1319639eaf.28.2024.08.03.23.56.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 03 Aug 2024 23:56:04 -0700 (PDT) Date: Sat, 3 Aug 2024 23:55:51 -0700 (PDT) From: Hugh Dickins To: Andrew Morton cc: Yu Zhao , Barry Song <21cnbao@gmail.com>, Hugh Dickins , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH mm-unstable v1 5/5] mm/swap: remove boilerplate In-Reply-To: <20240711021317.596178-6-yuzhao@google.com> Message-ID: <714e77d3-f629-bc06-4808-f7f33ac6872d@google.com> References: <20240711021317.596178-1-yuzhao@google.com> <20240711021317.596178-6-yuzhao@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Wed, 10 Jul 2024, Yu Zhao wrote: > Remove boilerplate by using a macro to choose the corresponding lock > and handler for each folio_batch in cpu_fbatches. > > Signed-off-by: Yu Zhao Andrew, please revert this "remove boilerplate" patch (and of course its followup fix) from mm-unstable. From the title I presume it was intended to make no functional change, but that's far from so. Under tmpfs swapping load, on different runs I see various badnesses: "Bad page" in __free_one_page(), Oops in __run_timer_base(), WARNING at kernel/workqueue.c:790 in set_work_data(), PageBuddy BUG at page-flags.h:1009 from __del_page_from_freelist(), something (I'd given up taking better notes by this time) in __queue_work(), others. All those were including the fix to Barry's report: without that fix, the boot is drowned in warnings scrolling past too fast to be read. (All the above were on the HP workstation, swapping to SSD; whereas on this ThinkPad, swapping to NVMe, no problem seen at all - I mention the swapping medium, but have no idea whether that's a relevant difference. In each case, MGLRU compiled in but not enabled. THPs and 64kTHPs active.) Sorry, but I've put no effort whatsoever into debugging this: "remove boilerplate" didn't seem worth the effort, and my personal preference is for readable boilerplate over hiding in a macro. If you prefer the macro, I expect Yu can soon come up with a fix (which I could test here): but for now please revert "remove boilerplate", since its issues get in the way of further mm testing. Thanks, Hugh > --- > mm/swap.c | 107 +++++++++++++++++++----------------------------------- > 1 file changed, 37 insertions(+), 70 deletions(-) > > diff --git a/mm/swap.c b/mm/swap.c > index 4a66d2f87f26..342ff4e39ba4 100644 > --- a/mm/swap.c > +++ b/mm/swap.c > @@ -220,16 +220,45 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn) > folios_put(fbatch); > } > > -static void folio_batch_add_and_move(struct folio_batch *fbatch, > - struct folio *folio, move_fn_t move_fn) > +static void __folio_batch_add_and_move(struct folio_batch *fbatch, > + struct folio *folio, move_fn_t move_fn, > + bool on_lru, bool disable_irq) > { > + unsigned long flags; > + > + folio_get(folio); > + > + if (on_lru && !folio_test_clear_lru(folio)) { > + folio_put(folio); > + return; > + } > + > if (folio_batch_add(fbatch, folio) && !folio_test_large(folio) && > !lru_cache_disabled()) > return; > > + if (disable_irq) > + local_lock_irqsave(&cpu_fbatches.lock_irq, flags); > + else > + local_lock(&cpu_fbatches.lock); > + > folio_batch_move_lru(fbatch, move_fn); > + > + if (disable_irq) > + local_unlock_irqrestore(&cpu_fbatches.lock_irq, flags); > + else > + local_unlock(&cpu_fbatches.lock); > } > > +#define folio_batch_add_and_move(folio, op, on_lru) \ > + __folio_batch_add_and_move( \ > + this_cpu_ptr(&cpu_fbatches.op), \ > + folio, \ > + op, \ > + on_lru, \ > + offsetof(struct cpu_fbatches, op) > offsetof(struct cpu_fbatches, lock_irq) \ > + ) > + > static void lru_move_tail(struct lruvec *lruvec, struct folio *folio) > { > if (folio_test_unevictable(folio)) > @@ -250,23 +279,11 @@ static void lru_move_tail(struct lruvec *lruvec, struct folio *folio) > */ > void folio_rotate_reclaimable(struct folio *folio) > { > - struct folio_batch *fbatch; > - unsigned long flags; > - > if (folio_test_locked(folio) || folio_test_dirty(folio) || > folio_test_unevictable(folio)) > return; > > - folio_get(folio); > - if (!folio_test_clear_lru(folio)) { > - folio_put(folio); > - return; > - } > - > - local_lock_irqsave(&cpu_fbatches.lock_irq, flags); > - fbatch = this_cpu_ptr(&cpu_fbatches.lru_move_tail); > - folio_batch_add_and_move(fbatch, folio, lru_move_tail); > - local_unlock_irqrestore(&cpu_fbatches.lock_irq, flags); > + folio_batch_add_and_move(folio, lru_move_tail, true); > } > > void lru_note_cost(struct lruvec *lruvec, bool file, > @@ -355,21 +372,10 @@ static void folio_activate_drain(int cpu) > > void folio_activate(struct folio *folio) > { > - struct folio_batch *fbatch; > - > if (folio_test_active(folio) || folio_test_unevictable(folio)) > return; > > - folio_get(folio); > - if (!folio_test_clear_lru(folio)) { > - folio_put(folio); > - return; > - } > - > - local_lock(&cpu_fbatches.lock); > - fbatch = this_cpu_ptr(&cpu_fbatches.lru_activate); > - folio_batch_add_and_move(fbatch, folio, lru_activate); > - local_unlock(&cpu_fbatches.lock); > + folio_batch_add_and_move(folio, lru_activate, true); > } > > #else > @@ -513,8 +519,6 @@ EXPORT_SYMBOL(folio_mark_accessed); > */ > void folio_add_lru(struct folio *folio) > { > - struct folio_batch *fbatch; > - > VM_BUG_ON_FOLIO(folio_test_active(folio) && > folio_test_unevictable(folio), folio); > VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); > @@ -524,11 +528,7 @@ void folio_add_lru(struct folio *folio) > lru_gen_in_fault() && !(current->flags & PF_MEMALLOC)) > folio_set_active(folio); > > - folio_get(folio); > - local_lock(&cpu_fbatches.lock); > - fbatch = this_cpu_ptr(&cpu_fbatches.lru_add); > - folio_batch_add_and_move(fbatch, folio, lru_add); > - local_unlock(&cpu_fbatches.lock); > + folio_batch_add_and_move(folio, lru_add, false); > } > EXPORT_SYMBOL(folio_add_lru); > > @@ -702,22 +702,11 @@ void lru_add_drain_cpu(int cpu) > */ > void deactivate_file_folio(struct folio *folio) > { > - struct folio_batch *fbatch; > - > /* Deactivating an unevictable folio will not accelerate reclaim */ > if (folio_test_unevictable(folio)) > return; > > - folio_get(folio); > - if (!folio_test_clear_lru(folio)) { > - folio_put(folio); > - return; > - } > - > - local_lock(&cpu_fbatches.lock); > - fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate_file); > - folio_batch_add_and_move(fbatch, folio, lru_deactivate_file); > - local_unlock(&cpu_fbatches.lock); > + folio_batch_add_and_move(folio, lru_deactivate_file, true); > } > > /* > @@ -730,21 +719,10 @@ void deactivate_file_folio(struct folio *folio) > */ > void folio_deactivate(struct folio *folio) > { > - struct folio_batch *fbatch; > - > if (folio_test_unevictable(folio) || !(folio_test_active(folio) || lru_gen_enabled())) > return; > > - folio_get(folio); > - if (!folio_test_clear_lru(folio)) { > - folio_put(folio); > - return; > - } > - > - local_lock(&cpu_fbatches.lock); > - fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate); > - folio_batch_add_and_move(fbatch, folio, lru_deactivate); > - local_unlock(&cpu_fbatches.lock); > + folio_batch_add_and_move(folio, lru_deactivate, true); > } > > /** > @@ -756,22 +734,11 @@ void folio_deactivate(struct folio *folio) > */ > void folio_mark_lazyfree(struct folio *folio) > { > - struct folio_batch *fbatch; > - > if (!folio_test_anon(folio) || !folio_test_swapbacked(folio) || > folio_test_swapcache(folio) || folio_test_unevictable(folio)) > return; > > - folio_get(folio); > - if (!folio_test_clear_lru(folio)) { > - folio_put(folio); > - return; > - } > - > - local_lock(&cpu_fbatches.lock); > - fbatch = this_cpu_ptr(&cpu_fbatches.lru_lazyfree); > - folio_batch_add_and_move(fbatch, folio, lru_lazyfree); > - local_unlock(&cpu_fbatches.lock); > + folio_batch_add_and_move(folio, lru_lazyfree, true); > } > > void lru_add_drain(void) > -- > 2.45.2.803.g4e1b14247a-goog