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author | Linus Walleij <linus.walleij@linaro.org> | 2015-12-21 09:36:21 +0100 |
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committer | Linus Walleij <linus.walleij@linaro.org> | 2015-12-21 09:36:21 +0100 |
commit | 0529357f102b96f68bc199f858d1c3b07f4b674c (patch) | |
tree | eaa047952a768099e00a5245afa0d84799df6990 /mm/backing-dev.c | |
parent | a9f1a3e4c1c7dc82711bc22dc52c7b0d6912ed56 (diff) | |
parent | 4ef7675344d687a0ef5b0d7c0cee12da005870c0 (diff) | |
download | op-kernel-dev-0529357f102b96f68bc199f858d1c3b07f4b674c.zip op-kernel-dev-0529357f102b96f68bc199f858d1c3b07f4b674c.tar.gz |
Merge tag 'v4.4-rc6' into devel
Linux 4.4-rc6
Diffstat (limited to 'mm/backing-dev.c')
-rw-r--r-- | mm/backing-dev.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 8ed2ffd..7340353 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -957,8 +957,9 @@ EXPORT_SYMBOL(congestion_wait); * jiffies for either a BDI to exit congestion of the given @sync queue * or a write to complete. * - * In the absence of zone congestion, cond_resched() is called to yield - * the processor if necessary but otherwise does not sleep. + * In the absence of zone congestion, a short sleep or a cond_resched is + * performed to yield the processor and to allow other subsystems to make + * a forward progress. * * The return value is 0 if the sleep is for the full timeout. Otherwise, * it is the number of jiffies that were still remaining when the function @@ -978,7 +979,19 @@ long wait_iff_congested(struct zone *zone, int sync, long timeout) */ if (atomic_read(&nr_wb_congested[sync]) == 0 || !test_bit(ZONE_CONGESTED, &zone->flags)) { - cond_resched(); + + /* + * Memory allocation/reclaim might be called from a WQ + * context and the current implementation of the WQ + * concurrency control doesn't recognize that a particular + * WQ is congested if the worker thread is looping without + * ever sleeping. Therefore we have to do a short sleep + * here rather than calling cond_resched(). + */ + if (current->flags & PF_WQ_WORKER) + schedule_timeout(1); + else + cond_resched(); /* In case we scheduled, work out time remaining */ ret = timeout - (jiffies - start); |