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Date: Wed, 8 Jul 2009 20:47:03 +0200
From: Jens Axboe <jens.axboe@...cle.com>
To: linux-kernel@...r.kernel.org
Cc: rjw@...k.pl, chris.mason@...cle.com
Subject: [PATCH] Fix congestion_wait() sync/async vs read/write confusion
Hi,
This one isn't great, we currently have broken congestion wait logic in
the kernel. 2.6.30 is impacted as well, so this patch should go to
stable too once it's in -git. I'll let this one simmer until tomorrow,
then ask Linus to pull it. The offending commit breaking this is
1faa16d22877f4839bd433547d770c676d1d964c.
Meanwhile, it could potentially cause buffered writeout slowdowns in the
kernel. Perhaps the 2.6.30 regression in that area is caused by this?
Would be interesting if the submitter could test. I can't find the list,
CC'ing Rafael.
diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c
index 7c8ca91..1f118d4 100644
--- a/arch/x86/lib/usercopy_32.c
+++ b/arch/x86/lib/usercopy_32.c
@@ -751,7 +751,7 @@ survive:
if (retval == -ENOMEM && is_global_init(current)) {
up_read(¤t->mm->mmap_sem);
- congestion_wait(WRITE, HZ/50);
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
goto survive;
}
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 83650e0..f7ebe74 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2595,7 +2595,7 @@ static int pkt_make_request(struct request_queue *q, struct bio *bio)
set_bdi_congested(&q->backing_dev_info, WRITE);
do {
spin_unlock(&pd->lock);
- congestion_wait(WRITE, HZ);
+ congestion_wait(BLK_RW_ASYNC, HZ);
spin_lock(&pd->lock);
} while(pd->bio_queue_size > pd->write_congestion_off);
}
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 9933eb8..529e2ba 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -776,7 +776,7 @@ static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
* But don't wait if split was due to the io size restriction
*/
if (unlikely(out_of_pages))
- congestion_wait(WRITE, HZ/100);
+ congestion_wait(BLK_RW_ASYNC, HZ/100);
/*
* With async crypto it is unsafe to share the crypto context
diff --git a/fs/fat/file.c b/fs/fat/file.c
index b28ea64..f042b96 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -134,7 +134,7 @@ static int fat_file_release(struct inode *inode, struct file *filp)
if ((filp->f_mode & FMODE_WRITE) &&
MSDOS_SB(inode->i_sb)->options.flush) {
fat_flush_inodes(inode->i_sb, inode, NULL);
- congestion_wait(WRITE, HZ/10);
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
}
return 0;
}
diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index 77f5bb7..9062220 100644
--- a/fs/reiserfs/journal.c
+++ b/fs/reiserfs/journal.c
@@ -997,7 +997,7 @@ static int reiserfs_async_progress_wait(struct super_block *s)
DEFINE_WAIT(wait);
struct reiserfs_journal *j = SB_JOURNAL(s);
if (atomic_read(&j->j_async_throttle))
- congestion_wait(WRITE, HZ / 10);
+ congestion_wait(BLK_RW_ASYNC, HZ / 10);
return 0;
}
diff --git a/fs/xfs/linux-2.6/kmem.c b/fs/xfs/linux-2.6/kmem.c
index 1cd3b55..2d3f90a 100644
--- a/fs/xfs/linux-2.6/kmem.c
+++ b/fs/xfs/linux-2.6/kmem.c
@@ -53,7 +53,7 @@ kmem_alloc(size_t size, unsigned int __nocast flags)
printk(KERN_ERR "XFS: possible memory allocation "
"deadlock in %s (mode:0x%x)\n",
__func__, lflags);
- congestion_wait(WRITE, HZ/50);
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
} while (1);
}
@@ -130,7 +130,7 @@ kmem_zone_alloc(kmem_zone_t *zone, unsigned int __nocast flags)
printk(KERN_ERR "XFS: possible memory allocation "
"deadlock in %s (mode:0x%x)\n",
__func__, lflags);
- congestion_wait(WRITE, HZ/50);
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
} while (1);
}
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 1418b91..0c93c7e 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -412,7 +412,7 @@ _xfs_buf_lookup_pages(
XFS_STATS_INC(xb_page_retries);
xfsbufd_wakeup(0, gfp_mask);
- congestion_wait(WRITE, HZ/50);
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
goto retry;
}
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 493b468..c86edd2 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -283,7 +283,6 @@ static wait_queue_head_t congestion_wqh[2] = {
__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
};
-
void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
{
enum bdi_state bit;
@@ -308,18 +307,18 @@ EXPORT_SYMBOL(set_bdi_congested);
/**
* congestion_wait - wait for a backing_dev to become uncongested
- * @rw: READ or WRITE
+ * @sync: SYNC or ASYNC IO
* @timeout: timeout in jiffies
*
* Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
* write congestion. If no backing_devs are congested then just wait for the
* next write to be completed.
*/
-long congestion_wait(int rw, long timeout)
+long congestion_wait(int sync, long timeout)
{
long ret;
DEFINE_WAIT(wait);
- wait_queue_head_t *wqh = &congestion_wqh[rw];
+ wait_queue_head_t *wqh = &congestion_wqh[sync];
prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
ret = io_schedule_timeout(timeout);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e2fa20d..e717964 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1973,7 +1973,7 @@ try_to_free:
if (!progress) {
nr_retries--;
/* maybe some writeback is necessary */
- congestion_wait(WRITE, HZ/10);
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
}
}
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 7687879..81627eb 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -575,7 +575,7 @@ static void balance_dirty_pages(struct address_space *mapping)
if (pages_written >= write_chunk)
break; /* We've done our duty */
- congestion_wait(WRITE, HZ/10);
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
}
if (bdi_nr_reclaimable + bdi_nr_writeback < bdi_thresh &&
@@ -669,7 +669,7 @@ void throttle_vm_writeout(gfp_t gfp_mask)
if (global_page_state(NR_UNSTABLE_NFS) +
global_page_state(NR_WRITEBACK) <= dirty_thresh)
break;
- congestion_wait(WRITE, HZ/10);
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
/*
* The caller might hold locks which can prevent IO completion
@@ -715,7 +715,7 @@ static void background_writeout(unsigned long _min_pages)
if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
/* Wrote less than expected */
if (wbc.encountered_congestion || wbc.more_io)
- congestion_wait(WRITE, HZ/10);
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
else
break;
}
@@ -787,7 +787,7 @@ static void wb_kupdate(unsigned long arg)
writeback_inodes(&wbc);
if (wbc.nr_to_write > 0) {
if (wbc.encountered_congestion || wbc.more_io)
- congestion_wait(WRITE, HZ/10);
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
else
break; /* All the old data is written */
}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e0f2cdf..2862bcf 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1666,7 +1666,7 @@ __alloc_pages_high_priority(gfp_t gfp_mask, unsigned int order,
preferred_zone, migratetype);
if (!page && gfp_mask & __GFP_NOFAIL)
- congestion_wait(WRITE, HZ/50);
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
} while (!page && (gfp_mask & __GFP_NOFAIL));
return page;
@@ -1831,7 +1831,7 @@ rebalance:
pages_reclaimed += did_some_progress;
if (should_alloc_retry(gfp_mask, order, pages_reclaimed)) {
/* Wait for some write requests to complete then retry */
- congestion_wait(WRITE, HZ/50);
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
goto rebalance;
}
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5415526..dea7abd 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1104,7 +1104,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
*/
if (nr_freed < nr_taken && !current_is_kswapd() &&
lumpy_reclaim) {
- congestion_wait(WRITE, HZ/10);
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
/*
* The attempt at page out may have made some
@@ -1721,7 +1721,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
/* Take a nap, wait for some writeback to complete */
if (sc->nr_scanned && priority < DEF_PRIORITY - 2)
- congestion_wait(WRITE, HZ/10);
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
}
/* top priority shrink_zones still had more to do? don't OOM, then */
if (!sc->all_unreclaimable && scanning_global_lru(sc))
@@ -1960,7 +1960,7 @@ loop_again:
* another pass across the zones.
*/
if (total_scanned && priority < DEF_PRIORITY - 2)
- congestion_wait(WRITE, HZ/10);
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
/*
* We do this so kswapd doesn't build up large priorities for
@@ -2233,7 +2233,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
goto out;
if (sc.nr_scanned && prio < DEF_PRIORITY - 2)
- congestion_wait(WRITE, HZ / 10);
+ congestion_wait(BLK_RW_ASYNC, HZ / 10);
}
}
--
Jens Axboe
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