On Mon, 17 Dec 2012 23:24:14 +0100
Michal Nazarewicz <mina86@xxxxxxxxxx> wrote:
> [+marek]
>
> On Mon, Dec 17 2012, Srinivas Pandruvada wrote:
> > As per documentation and other places calling putback_lru_pages,
> > on error only, except for CMA. I am not sure this is a problem
> > for CMA or not.
>
> If ret >= 0 than the list is empty anyway so the effect of this patch is
> to save a function call. It's also true that other callers call it only
> on error so __alloc_contig_migrate_range() is an odd man out here. As
> such:
>
> Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
__alloc_contig_migrate_range() is a bit twisty. How does this look?
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: mm/page_alloc.c:__alloc_contig_migrate_range(): cleanup
- `ret' is always zero in the we-timed-out case
- remove a test-n-branch in the wrapup code
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff -puN mm/page_alloc.c~mm-page_allocc-__alloc_contig_migrate_range-cleanup mm/page_alloc.c
--- a/mm/page_alloc.c~mm-page_allocc-__alloc_contig_migrate_range-cleanup
+++ a/mm/page_alloc.c
@@ -5804,7 +5804,6 @@ static int __alloc_contig_migrate_range(
}
tries = 0;
} else if (++tries == 5) {
- ret = ret < 0 ? ret : -EBUSY;
break;
}
@@ -5817,9 +5816,11 @@ static int __alloc_contig_migrate_range(
0, false, MIGRATE_SYNC,
MR_CMA);
}
- if (ret < 0)
+ if (ret < 0) {
putback_movable_pages(&cc->migratepages);
- return ret > 0 ? 0 : ret;
+ return ret;
+ }
+ return 0;
}
/**
_
Also, what's happening here?
pfn = isolate_migratepages_range(cc->zone, cc,
pfn, end, true);
if (!pfn) {
ret = -EINTR;
break;
}
The isolate_migratepages_range() return value is undocumented and
appears to make no sense. It returns zero if fatal_signal_pending()
and if too_many_isolated&&!cc->sync. Returning -EINTR in the latter
case is daft.
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