The patch titled
Subject: mm: fs: invalidate BH LRU during page migration
has been added to the -mm tree. Its filename is
mm-fs-invalidate-bh-lru-during-page-migration.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-fs-invalidate-bh-lru-during-page-migration.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-fs-invalidate-bh-lru-during-page-migration.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: mm: fs: invalidate BH LRU during page migration
Pages containing buffer_heads that are in one of the per-CPU buffer_head
LRU caches will be pinned and thus cannot be migrated. This can prevent
CMA allocations from succeeding, which are often used on platforms with
co-processors (such as a DSP) that can only use physically contiguous
memory. It can also prevent memory hot-unplugging from succeeding, which
involves migrating at least MIN_MEMORY_BLOCK_SIZE bytes of memory, which
ranges from 8 MiB to 1 GiB based on the architecture in use.
Correspondingly, invalidate the BH LRU caches before a migration starts
and stop any buffer_head from being cached in the LRU caches, until
migration has finished.
Link: https://lkml.kernel.org/r/20210319175127.886124-3-minchan@xxxxxxxxxx
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Chris Goldsworthy <cgoldswo@xxxxxxxxxxxxxx>
Tested-by: Oliver Sang <oliver.sang@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: John Dias <joaodias@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/buffer.c | 36 ++++++++++++++++++++++++++++------
include/linux/buffer_head.h | 4 +++
mm/swap.c | 5 +++-
3 files changed, 38 insertions(+), 7 deletions(-)
--- a/fs/buffer.c~mm-fs-invalidate-bh-lru-during-page-migration
+++ a/fs/buffer.c
@@ -1264,6 +1264,15 @@ static void bh_lru_install(struct buffer
int i;
check_irqs_on();
+ /*
+ * the refcount of buffer_head in bh_lru prevents dropping the
+ * attached page(i.e., try_to_free_buffers) so it could cause
+ * failing page migration.
+ * Skip putting upcoming bh into bh_lru until migration is done.
+ */
+ if (lru_cache_disabled())
+ return;
+
bh_lru_lock();
b = this_cpu_ptr(&bh_lrus);
@@ -1404,6 +1413,15 @@ __bread_gfp(struct block_device *bdev, s
}
EXPORT_SYMBOL(__bread_gfp);
+static void __invalidate_bh_lrus(struct bh_lru *b)
+{
+ int i;
+
+ for (i = 0; i < BH_LRU_SIZE; i++) {
+ brelse(b->bhs[i]);
+ b->bhs[i] = NULL;
+ }
+}
/*
* invalidate_bh_lrus() is called rarely - but not only at unmount.
* This doesn't race because it runs in each cpu either in irq
@@ -1412,16 +1430,12 @@ EXPORT_SYMBOL(__bread_gfp);
static void invalidate_bh_lru(void *arg)
{
struct bh_lru *b = &get_cpu_var(bh_lrus);
- int i;
- for (i = 0; i < BH_LRU_SIZE; i++) {
- brelse(b->bhs[i]);
- b->bhs[i] = NULL;
- }
+ __invalidate_bh_lrus(b);
put_cpu_var(bh_lrus);
}
-static bool has_bh_in_lru(int cpu, void *dummy)
+bool has_bh_in_lru(int cpu, void *dummy)
{
struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu);
int i;
@@ -1440,6 +1454,16 @@ void invalidate_bh_lrus(void)
}
EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
+void invalidate_bh_lrus_cpu(int cpu)
+{
+ struct bh_lru *b;
+
+ bh_lru_lock();
+ b = per_cpu_ptr(&bh_lrus, cpu);
+ __invalidate_bh_lrus(b);
+ bh_lru_unlock();
+}
+
void set_bh_page(struct buffer_head *bh,
struct page *page, unsigned long offset)
{
--- a/include/linux/buffer_head.h~mm-fs-invalidate-bh-lru-during-page-migration
+++ a/include/linux/buffer_head.h
@@ -194,6 +194,8 @@ void __breadahead_gfp(struct block_devic
struct buffer_head *__bread_gfp(struct block_device *,
sector_t block, unsigned size, gfp_t gfp);
void invalidate_bh_lrus(void);
+void invalidate_bh_lrus_cpu(int cpu);
+bool has_bh_in_lru(int cpu, void *dummy);
struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
void free_buffer_head(struct buffer_head * bh);
void unlock_buffer(struct buffer_head *bh);
@@ -406,6 +408,8 @@ static inline int inode_has_buffers(stru
static inline void invalidate_inode_buffers(struct inode *inode) {}
static inline int remove_inode_buffers(struct inode *inode) { return 1; }
static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
+static inline void invalidate_bh_lrus_cpu(int cpu) {}
+static inline bool has_bh_in_lru(int cpu, void *dummy) { return 0; }
#define buffer_heads_over_limit 0
#endif /* CONFIG_BLOCK */
--- a/mm/swap.c~mm-fs-invalidate-bh-lru-during-page-migration
+++ a/mm/swap.c
@@ -36,6 +36,7 @@
#include <linux/hugetlb.h>
#include <linux/page_idle.h>
#include <linux/local_lock.h>
+#include <linux/buffer_head.h>
#include "internal.h"
@@ -641,6 +642,7 @@ void lru_add_drain_cpu(int cpu)
pagevec_lru_move_fn(pvec, lru_lazyfree_fn);
activate_page_drain(cpu);
+ invalidate_bh_lrus_cpu(cpu);
}
/**
@@ -828,7 +830,8 @@ inline void __lru_add_drain_all(bool for
pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) ||
pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, cpu)) ||
pagevec_count(&per_cpu(lru_pvecs.lru_lazyfree, cpu)) ||
- need_activate_page_drain(cpu)) {
+ need_activate_page_drain(cpu) ||
+ has_bh_in_lru(cpu, NULL)) {
INIT_WORK(work, lru_add_drain_per_cpu);
queue_work_on(cpu, mm_percpu_wq, work);
__cpumask_set_cpu(cpu, &has_work);
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
mm-remove-lru_add_drain_all-in-alloc_contig_range.patch
mm-page_alloc-dump-migrate-failed-pages.patch
mm-disable-lru-pagevec-during-the-migration-temporarily.patch
mm-replace-migrate_-with-lru_cache_.patch
mm-fs-invalidate-bh-lru-during-page-migration.patch
mm-vmstat-add-cma-statistics.patch
mm-cma-support-sysfs.patch
