During compaction isolated free pages are marked allocated so that they
can be split and/or freed.  For that, post_alloc_hook() is used inside
split_map_pages() and release_free_list().  split_map_pages() marks free
pages allocated, splits the pages and then lets
alloc_contig_range_noprof() free those pages.  release_free_list() marks
free pages and immediately frees them.  This usage of post_alloc_hook()
affect memory allocation profiling because these functions might not be
called from an instrumented allocator, therefore current->alloc_tag is
NULL and when debugging is enabled (CONFIG_MEM_ALLOC_PROFILING_DEBUG=y)
that causes warnings.  To avoid that, wrap such post_alloc_hook() calls
into an instrumented function which acts as an allocator which will be
charged for these fake allocations.  Note that these allocations are very
short lived until they are freed, therefore the associated counters should
usually read 0.

Link: https://lkml.kernel.org/r/20240614230504.3849136-1-surenb@google.comSigned-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Sourav Panda <souravpanda@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>