Commit afb99e9f authored by Hugh Dickins's avatar Hugh Dickins Committed by Andrew Morton
Browse files

mm: revert "mm/gup: clear the LRU flag of a page before adding to LRU batch" 

This reverts commit 33dfe920: now that
collect_longterm_unpinnable_folios() is checking ref_count instead of lru,
and mlock/munlock do not participate in the revised LRU flag clearing,
those changes are misleading, and enlarge the window during which
mlock/munlock may miss an mlock_count update.

It is possible (I'd hesitate to claim probable) that the greater
likelihood of missed mlock_count updates would explain the "Realtime
threads delayed due to kcompactd0" observed on 6.12 in the Link below.  If
that is the case, this reversion will help; but a complete solution needs
also a further patch, beyond the scope of this series.

Included some 80-column cleanup around folio_batch_add_and_move().

The role of folio_test_clear_lru() (before taking per-memcg lru_lock) is
questionable since 6.13 removed mem_cgroup_move_account() etc; but perhaps
there are still some races which need it - not examined here.

Link: https://lore.kernel.org/linux-mm/DU0PR01MB10385345F7153F334100981888259A@DU0PR01MB10385.eurprd01.prod.exchangelabs.com/
Link: https://lkml.kernel.org/r/05905d7b-ed14-68b1-79d8-bdec30367eba@google.com


Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Keir Fraser <keirf@google.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Li Zhe <lizhe.67@bytedance.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shivank Garg <shivankg@amd.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Xu <weixugc@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: yangge <yangge1116@126.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a09a8a1f

mm/swap.c

+26 −24
Original line number Diff line number Diff line
@@ -164,6 +164,10 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn) 
	for (i = 0; i < folio_batch_count(fbatch); i++) {

		struct folio *folio = fbatch->folios[i];



		/* block memcg migration while the folio moves between lru */

		if (move_fn != lru_add && !folio_test_clear_lru(folio))

			continue;



		folio_lruvec_relock_irqsave(folio, &lruvec, &flags);

		move_fn(lruvec, folio);
@@ -176,14 +180,10 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn) 
}



static void __folio_batch_add_and_move(struct folio_batch __percpu *fbatch,

		struct folio *folio, move_fn_t move_fn,

		bool on_lru, bool disable_irq)

		struct folio *folio, move_fn_t move_fn, bool disable_irq)

{

	unsigned long flags;



	if (on_lru && !folio_test_clear_lru(folio))

		return;



	folio_get(folio);



	if (disable_irq)
@@ -191,8 +191,8 @@ static void __folio_batch_add_and_move(struct folio_batch __percpu *fbatch, 
	else

		local_lock(&cpu_fbatches.lock);



	if (!folio_batch_add(this_cpu_ptr(fbatch), folio) || folio_test_large(folio) ||

	    lru_cache_disabled())

	if (!folio_batch_add(this_cpu_ptr(fbatch), folio) ||

			folio_test_large(folio) || lru_cache_disabled())

		folio_batch_move_lru(this_cpu_ptr(fbatch), move_fn);



	if (disable_irq)
@@ -201,13 +201,13 @@ static void __folio_batch_add_and_move(struct folio_batch __percpu *fbatch, 
		local_unlock(&cpu_fbatches.lock);

}



#define folio_batch_add_and_move(folio, op, on_lru)						\

#define folio_batch_add_and_move(folio, op)		\

	__folio_batch_add_and_move(			\

		&cpu_fbatches.op,			\

		folio,					\

		op,					\

		on_lru,										\

		offsetof(struct cpu_fbatches, op) >= offsetof(struct cpu_fbatches, lock_irq)	\

		offsetof(struct cpu_fbatches, op) >=	\

		offsetof(struct cpu_fbatches, lock_irq)	\

	)



static void lru_move_tail(struct lruvec *lruvec, struct folio *folio)
@@ -231,10 +231,10 @@ static void lru_move_tail(struct lruvec *lruvec, struct folio *folio) 
void folio_rotate_reclaimable(struct folio *folio)

{

	if (folio_test_locked(folio) || folio_test_dirty(folio) ||

	    folio_test_unevictable(folio))

	    folio_test_unevictable(folio) || !folio_test_lru(folio))

		return;



	folio_batch_add_and_move(folio, lru_move_tail, true);

	folio_batch_add_and_move(folio, lru_move_tail);

}



void lru_note_cost_unlock_irq(struct lruvec *lruvec, bool file,
@@ -328,10 +328,11 @@ static void folio_activate_drain(int cpu) 


void folio_activate(struct folio *folio)

{

	if (folio_test_active(folio) || folio_test_unevictable(folio))

	if (folio_test_active(folio) || folio_test_unevictable(folio) ||

	    !folio_test_lru(folio))

		return;



	folio_batch_add_and_move(folio, lru_activate, true);

	folio_batch_add_and_move(folio, lru_activate);

}



#else
@@ -507,7 +508,7 @@ void folio_add_lru(struct folio *folio) 
	    lru_gen_in_fault() && !(current->flags & PF_MEMALLOC))

		folio_set_active(folio);



	folio_batch_add_and_move(folio, lru_add, false);

	folio_batch_add_and_move(folio, lru_add);

}

EXPORT_SYMBOL(folio_add_lru);
@@ -685,13 +686,13 @@ void lru_add_drain_cpu(int cpu) 
void deactivate_file_folio(struct folio *folio)

{

	/* Deactivating an unevictable folio will not accelerate reclaim */

	if (folio_test_unevictable(folio))

	if (folio_test_unevictable(folio) || !folio_test_lru(folio))

		return;



	if (lru_gen_enabled() && lru_gen_clear_refs(folio))

		return;



	folio_batch_add_and_move(folio, lru_deactivate_file, true);

	folio_batch_add_and_move(folio, lru_deactivate_file);

}



/*
@@ -704,13 +705,13 @@ void deactivate_file_folio(struct folio *folio) 
 */

void folio_deactivate(struct folio *folio)

{

	if (folio_test_unevictable(folio))

	if (folio_test_unevictable(folio) || !folio_test_lru(folio))

		return;



	if (lru_gen_enabled() ? lru_gen_clear_refs(folio) : !folio_test_active(folio))

		return;



	folio_batch_add_and_move(folio, lru_deactivate, true);

	folio_batch_add_and_move(folio, lru_deactivate);

}



/**
@@ -723,10 +724,11 @@ void folio_deactivate(struct folio *folio) 
void folio_mark_lazyfree(struct folio *folio)

{

	if (!folio_test_anon(folio) || !folio_test_swapbacked(folio) ||

	    !folio_test_lru(folio) ||

	    folio_test_swapcache(folio) || folio_test_unevictable(folio))

		return;



	folio_batch_add_and_move(folio, lru_lazyfree, true);

	folio_batch_add_and_move(folio, lru_lazyfree);

}



void lru_add_drain(void)