| Message ID | 20240514065933.1523170-1-yajun.deng@linux.dev (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: page_alloc: fix the incorrect parameter | expand |
On Tue, May 14, 2024 at 02:59:33PM +0800, Yajun Deng wrote: > The first parameter passed to set_pageblock_migratetype should be the > buddy, not the page. Let's change it back correctly. No it shouldn't be. > Fixes: fd919a85cd55 ("mm: page_isolation: prepare for hygienic freelists") > Signed-off-by: Yajun Deng <yajun.deng@linux.dev> > --- > mm/page_alloc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index cd584aace6bf..5422f6f8975d 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1728,7 +1728,7 @@ bool move_freepages_block_isolate(struct zone *zone, struct page *page, > > del_page_from_free_list(buddy, zone, order, > get_pfnblock_migratetype(buddy, pfn)); > - set_pageblock_migratetype(page, migratetype); > + set_pageblock_migratetype(buddy, migratetype); > split_large_buddy(zone, buddy, pfn, order); [ pageblock | pageblock ] ^ ^ buddy page We're trying to isolate the second pageblock, but it's part of a bigger buddy. Remove buddy from the free list, update the migratetype of page, then split and free the chunks back. This puts the first pageblock back on the original freelist and the second block onto the isolate list. In the else branch, it's the first block we're interested in: [ pageblock | pageblock ] ^ page So again, take the whole thing off, but now mark the first block isolate, then split and free.
May 14, 2024 at 8:40 PM, "Johannes Weiner" <hannes@cmpxchg.org> wrote: > > On Tue, May 14, 2024 at 02:59:33PM +0800, Yajun Deng wrote: > > > > > The first parameter passed to set_pageblock_migratetype should be the > > > > buddy, not the page. Let's change it back correctly. > > > > No it shouldn't be. > > > > > Fixes: fd919a85cd55 ("mm: page_isolation: prepare for hygienic freelists") > > > > Signed-off-by: Yajun Deng <yajun.deng@linux.dev> > > > > --- > > > > mm/page_alloc.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > > > index cd584aace6bf..5422f6f8975d 100644 > > > > --- a/mm/page_alloc.c > > > > +++ b/mm/page_alloc.c > > > > @@ -1728,7 +1728,7 @@ bool move_freepages_block_isolate(struct zone *zone, struct page *page, > > > > > > > > del_page_from_free_list(buddy, zone, order, > > > > get_pfnblock_migratetype(buddy, pfn)); > > > > - set_pageblock_migratetype(page, migratetype); > > > > + set_pageblock_migratetype(buddy, migratetype); > > > > split_large_buddy(zone, buddy, pfn, order); > > > > [ pageblock | pageblock ] > > ^ ^ > > buddy page > > We're trying to isolate the second pageblock, but it's part of a > > bigger buddy. Remove buddy from the free list, update the migratetype > > of page, then split and free the chunks back. This puts the first > > pageblock back on the original freelist and the second block onto the > > isolate list. > > In the else branch, it's the first block we're interested in: > > [ pageblock | pageblock ] > > ^ > > page > > So again, take the whole thing off, but now mark the first block > > isolate, then split and free. > Got it, thank you for your detailed explanation.
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index cd584aace6bf..5422f6f8975d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1728,7 +1728,7 @@ bool move_freepages_block_isolate(struct zone *zone, struct page *page, del_page_from_free_list(buddy, zone, order, get_pfnblock_migratetype(buddy, pfn)); - set_pageblock_migratetype(page, migratetype); + set_pageblock_migratetype(buddy, migratetype); split_large_buddy(zone, buddy, pfn, order); return true; }
The first parameter passed to set_pageblock_migratetype should be the buddy, not the page. Let's change it back correctly. Fixes: fd919a85cd55 ("mm: page_isolation: prepare for hygienic freelists") Signed-off-by: Yajun Deng <yajun.deng@linux.dev> --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)