Commit 232ea4d6 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds

[PATCH] throttle_vm_writeout(): don't loop on GFP_NOFS and GFP_NOIO allocations

throttle_vm_writeout() is designed to wait for the dirty levels to subside.
But if the caller holds IO or FS locks, we might be holding up that writeout.

So change it to take a single nap to give other devices a chance to clean some
memory, then return.

Cc: Nick Piggin <>
Cc: OGAWA Hirofumi <>
Cc: Kumar Gala <>
Cc: Pete Zaitcev <>
Cc: <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent b1a316f6
......@@ -84,7 +84,7 @@ static inline void wait_on_inode(struct inode *inode)
int wakeup_pdflush(long nr_pages);
void laptop_io_completion(void);
void laptop_sync_completion(void);
void throttle_vm_writeout(void);
void throttle_vm_writeout(gfp_t gfp_mask);
/* These are exported to sysctl. */
extern int dirty_background_ratio;
......@@ -296,11 +296,21 @@ void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
void throttle_vm_writeout(void)
void throttle_vm_writeout(gfp_t gfp_mask)
long background_thresh;
long dirty_thresh;
if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) {
* The caller might hold locks which can prevent IO completion
* or progress in the filesystem. So we cannot just sit here
* waiting for IO to complete.
congestion_wait(WRITE, HZ/10);
for ( ; ; ) {
get_dirty_limits(&background_thresh, &dirty_thresh, NULL);
......@@ -317,7 +327,6 @@ void throttle_vm_writeout(void)
* writeback at least _min_pages, and keep writing until the amount of dirty
* memory is less than the background threshold, or until we're all clean.
......@@ -952,7 +952,7 @@ static unsigned long shrink_zone(int priority, struct zone *zone,
return nr_reclaimed;
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