mm/page_alloc: apply per-task GFP context in bulk allocator

alloc_pages_bulk_noprof() does not call current_gfp_context(), so per-task
scoped allocation constraints (PF_MEMALLOC_NOIO, PF_MEMALLOC_NOFS,
PF_MEMALLOC_PIN) are not applied on the bulk fast path.

By ignoring PF_MEMALLOC_NOIO and PF_MEMALLOC_NOFS, the allocation can
theoretically result in a deadlock.

Ignoring PF_MEMALLOC_PIN also has consequences: without clearing
__GFP_MOVABLE, prepare_alloc_pages() selects MIGRATE_MOVABLE for the PCP
list, and a task with PF_MEMALLOC_PIN set receives movable pages from the
bulk allocator.  Once pinned, these pages can no longer be migrated but
remain in MOVABLE pageblocks, violating the mobility contract.  This can
increase fragmentation and interfere with compaction or contiguous-memory
allocations, eventually surfacing as higher allocation latency or
allocation failures under memory pressure.

Found via review of the bulk allocation tracepoint hooks [1].

Link: https://sashiko.dev/#/patchset/20260907120949.418450-1-liuqiqi%40kylinos.cn
Link: https://lore.kernel.org/all/20260907120949.418450-1-liuqiqi@kylinos.cn/ [1]
Link: https://lore.kernel.org/20260915074928.327471-1-liuqiqi@kylinos.cn
Fixes: 387ba26fb1cb ("mm/page_alloc: add a bulk page allocator")
Signed-off-by: Qiqi Liu <liuqiqi@kylinos.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>

0 files changed, 0 insertions, 0 deletions