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authorMinchan Kim <minchan@kernel.org>2021-05-05 04:37:00 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-05 21:27:24 +0300
commit8cc621d2f45ddd3dc664024a647ee7adf48d79a5 (patch)
tree5631d2a5224949098bc2d928f673e6baa1c7e3e6 /fs/buffer.c
parent361a2a229fa31ab7f2b236b5946e434964d00762 (diff)
downloadlinux-8cc621d2f45ddd3dc664024a647ee7adf48d79a5.tar.xz
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@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Reported-by: Chris Goldsworthy <cgoldswo@codeaurora.org> Reported-by: Laura Abbott <labbott@kernel.org> Tested-by: Oliver Sang <oliver.sang@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: John Dias <joaodias@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/buffer.c')
-rw-r--r--fs/buffer.c36
1 files changed, 30 insertions, 6 deletions
diff --git a/fs/buffer.c b/fs/buffer.c
index 0cb7ffd4977c..e9872d0dcbf1 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1264,6 +1264,15 @@ static void bh_lru_install(struct buffer_head *bh)
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, sector_t block,
}
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)
{