Re: [fuse-devel] [PATCH 14/14] mm: Account for WRITEBACK_TEMP inbalance_dirty_pages

From: Maxim V. Patlasov
Date: Thu Apr 25 2013 - 10:32:29 EST

Hi Miklos,

04/01/2013 02:42 PM, Maxim V. Patlasov ÐÐÑÐÑ:
Make balance_dirty_pages start the throttling when the WRITEBACK_TEMP
counter is high enough. This prevents us from having too many dirty
pages on fuse, thus giving the userspace part of it a chance to write
stuff properly.

Note, that the existing balance logic is per-bdi, i.e. if the fuse
user task gets stuck in the function this means, that it either
writes to the mountpoint it serves (but it can deadlock even without
the writeback) or it is writing to some _other_ dirty bdi and in the
latter case someone else will free the memory for it.

Signed-off-by: Maxim Patlasov <MPatlasov@xxxxxxxxxxxxx>
Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxx>
mm/page-writeback.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 0713bfb..c47bcd4 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1235,7 +1235,8 @@ static void balance_dirty_pages(struct address_space *mapping,
nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
- nr_dirty = nr_reclaimable + global_page_state(NR_WRITEBACK);
+ nr_dirty = nr_reclaimable + global_page_state(NR_WRITEBACK) +
+ global_page_state(NR_WRITEBACK_TEMP);
global_dirty_limits(&background_thresh, &dirty_thresh);

Please drop this patch. As we discussed in LSF/MM, the fix above is correct, but it's not enough: we also need to ensure disregard of NR_WRITEBACK_TEMP when balance_dirty_pages() is called from fuse daemon. I'll send a separate patch-set soon.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at