On Wed, Apr 09, 2025 at 02:12:40PM -0700, Andrew Morton wrote:
The patch titled Subject: alloc_tag: handle incomplete bulk allocations in vm_module_tags_populate has been added to the -mm mm-hotfixes-unstable branch. Its filename is alloc_tag-handle-incomplete-bulk-allocations-in-vm_module_tags_populate.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days
I don't think we want to rush this patch, given that it's not fixing an actual crash.
I'm currently chasing a crash (null ptr deref, slab obj extension vector seems to not be getting allocated correctly) in 6.15-rc1, so I'm wondering what's missing in our test coverage.
From: "T.J. Mercier" tjmercier@google.com Subject: alloc_tag: handle incomplete bulk allocations in vm_module_tags_populate Date: Wed, 9 Apr 2025 19:54:47 +0000
alloc_pages_bulk_node may partially succeed and allocate fewer than the requested nr_pages. There are several conditions under which this can occur, but we have encountered the case where CONFIG_PAGE_OWNER is enabled causing all bulk allocations to always fallback to single page allocations due to commit 187ad460b841 ("mm/page_alloc: avoid page allocator recursion with pagesets.lock held").
Currently vm_module_tags_populate immediately fails when alloc_pages_bulk_node returns fewer than the requested number of pages. This patch causes vm_module_tags_populate to retry bulk allocations for the remaining memory instead.
Link: https://lkml.kernel.org/r/20250409195448.3697351-1-tjmercier@google.com Fixes: 187ad460b841 ("mm/page_alloc: avoid page allocator recursion with pagesets.lock held") Signed-off-by: T.J. Mercier tjmercier@google.com Reported-by: Janghyuck Kim janghyuck.kim@samsung.com Cc: Kent Overstreet kent.overstreet@linux.dev Cc: Suren Baghdasaryan surenb@google.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org
lib/alloc_tag.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)
--- a/lib/alloc_tag.c~alloc_tag-handle-incomplete-bulk-allocations-in-vm_module_tags_populate +++ a/lib/alloc_tag.c @@ -422,11 +422,20 @@ static int vm_module_tags_populate(void) unsigned long old_shadow_end = ALIGN(phys_end, MODULE_ALIGN); unsigned long new_shadow_end = ALIGN(new_end, MODULE_ALIGN); unsigned long more_pages;
unsigned long nr;
unsigned long nr = 0;more_pages = ALIGN(new_end - phys_end, PAGE_SIZE) >> PAGE_SHIFT;
nr = alloc_pages_bulk_node(GFP_KERNEL | __GFP_NOWARN,NUMA_NO_NODE, more_pages, next_page);
while (nr < more_pages) {unsigned long allocated;allocated = alloc_pages_bulk_node(GFP_KERNEL | __GFP_NOWARN,NUMA_NO_NODE, more_pages - nr, next_page + nr);if (!allocated)break;nr += allocated;}- if (nr < more_pages || vmap_pages_range(phys_end, phys_end + (nr << PAGE_SHIFT), PAGE_KERNEL, next_page, PAGE_SHIFT) < 0) {
_
Patches currently in -mm which might be from tjmercier@google.com are
alloc_tag-handle-incomplete-bulk-allocations-in-vm_module_tags_populate.patch