Re: Userland swsusp failure (mm-related)

["Rafael J. Wysocki" <rjw@sisk.pl>]

Hi,

On Sunday 09 April 2006 03:51, Nick Piggin wrote:
> Rafael J. Wysocki wrote:
> >>>Well, it looks like we didn't free enough RAM for suspend in this case.
> >>>Unfortunately we were below the min watermark for ZONE_NORMAL and
> >>>we tried to allocate with GFP_ATOMIC (Nick, shouldn't we fall back to
> >>>ZONE_DMA in this case?).
> >>>
> >>>I think we can safely ignore the watermarks in swsusp, so probably
> >>>we can set PF_MEMALLOC for the current task temporarily and reset
> >>>it when we have allocated memory.  Pavel, what do you think?
> >>
> >>Seems little hacky but okay to me.
> >>
> >>Should not fixing "how much to free" computation to free a bit more be
> >>enough to handle this?
> > 
> > 
> > Yes, but in that case we'll leave some memory unused. ;-)
> > 
> 
> Probably doesn't fall back to ZONE_DMA because of lowmem reserve.
> Yes, PF_MEMALLOC sounds like it might do what you want. A little
> hackish perhaps, but better than putting swsusp special cases
> into page_alloc.c.

The appended patch contains the changes I'd like to make.  Pavel, is that
acceptable?

Rafael

---
 kernel/power/snapshot.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

Index: linux-2.6.17-rc1-mm2/kernel/power/snapshot.c
===================================================================
--- linux-2.6.17-rc1-mm2.orig/kernel/power/snapshot.c	2006-04-08 21:29:55.000000000 +0200
+++ linux-2.6.17-rc1-mm2/kernel/power/snapshot.c	2006-04-11 22:09:28.000000000 +0200
@@ -461,17 +461,23 @@ static struct pbe *swsusp_alloc(unsigned
 {
 	struct pbe *pblist;
 
+	/* We don't want to be affected by zone watermarks etc. */
+	current->flags |= PF_MEMALLOC;
+
 	if (!(pblist = alloc_pagedir(nr_pages, GFP_ATOMIC | __GFP_COLD, 0))) {
 		printk(KERN_ERR "suspend: Allocating pagedir failed.\n");
-		return NULL;
+		goto out;
 	}
 
 	if (alloc_data_pages(pblist, GFP_ATOMIC | __GFP_COLD, 0)) {
 		printk(KERN_ERR "suspend: Allocating image pages failed.\n");
 		swsusp_free();
-		return NULL;
+		pblist = NULL;
 	}
 
+out:
+	current->flags &= ~PF_MEMALLOC;
+
 	return pblist;
 }