| Message ID | 20250326031218.487450-1-wangchuanguo@inspur.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: migrate: restore the nmask after successfully allocating on the target node | expand |
On Wed, Mar 26, 2025 at 11:12:18AM +0800, wangchuanguo wrote: > If memory is successfully allocated on the target node and the > function directly returns without value restore for nmask, > non-first migration operations in migrate_pages() by again label > may ignore the nmask settings, thereby allowing new memory > allocations for migration on any node. I have no opinion on whether this is the right thing to do or not, but if it is: > +++ b/mm/vmscan.c > @@ -1026,8 +1026,10 @@ struct folio *alloc_migrate_folio(struct folio *src, unsigned long private) > mtc->nmask = NULL; > mtc->gfp_mask |= __GFP_THISNODE; > dst = alloc_migration_target(src, (unsigned long)mtc); > - if (dst) > + if (dst) { > + mtc->nmask = allowed_mask; > return dst; > + } > > mtc->gfp_mask &= ~__GFP_THISNODE; > mtc->nmask = allowed_mask; this should be: dst = alloc_migration_target(src, (unsigned long)mtc); + mtc->nmask = allowed_mask; if (dst) return dst; mtc->gfp_mask &= ~__GFP_THISNODE; - mtc->nmask = allowed_mask;
On Wed, Mar 26, 2025 at 11:12:18AM +0800, wangchuanguo wrote: > If memory is successfully allocated on the target node and the > function directly returns without value restore for nmask, > non-first migration operations in migrate_pages() by again label > may ignore the nmask settings, thereby allowing new memory > allocations for migration on any node. > > Signed-off-by: wangchuanguo <wangchuanguo@inspur.com> Unless I am missing something this looks reasonable, but I whonder why nobody noticed it before. It is a path that should be pretty exercised.
diff --git a/mm/vmscan.c b/mm/vmscan.c index b620d74b0f66..9467b2acef28 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1026,8 +1026,10 @@ struct folio *alloc_migrate_folio(struct folio *src, unsigned long private) mtc->nmask = NULL; mtc->gfp_mask |= __GFP_THISNODE; dst = alloc_migration_target(src, (unsigned long)mtc); - if (dst) + if (dst) { + mtc->nmask = allowed_mask; return dst; + } mtc->gfp_mask &= ~__GFP_THISNODE; mtc->nmask = allowed_mask;
If memory is successfully allocated on the target node and the function directly returns without value restore for nmask, non-first migration operations in migrate_pages() by again label may ignore the nmask settings, thereby allowing new memory allocations for migration on any node. Signed-off-by: wangchuanguo <wangchuanguo@inspur.com> --- mm/vmscan.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)