linux-kernel - Re: [PATCH] alloc_tag: Handle incomplete bulk allocations in vm_module_tags

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Message-Id: <20250409141131.bd67f6b19ea7e770dce40ac7@linux-foundation.org>
Date: Wed, 9 Apr 2025 14:11:31 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: "T.J. Mercier" <tjmercier@...gle.com>, Suren Baghdasaryan
 <surenb@...gle.com>, Kent Overstreet <kent.overstreet@...ux.dev>, Janghyuck
 Kim <janghyuck.kim@...sung.com>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] alloc_tag: Handle incomplete bulk allocations in
 vm_module_tags_populate

On Wed, 9 Apr 2025 14:08:48 -0700 Andrew Morton <akpm@...ux-foundation.org> wrote:

> On Wed,  9 Apr 2025 19:54:47 +0000 "T.J. Mercier" <tjmercier@...gle.com> wrote:
> 
> > 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.
> 
> Please describe the userspace-visible runtime effects of this change.  In a way
> which permits a user who is experiencing some problem can recognize that this
> patch will address that problem.
>
> ...
>
> Reported-by: Janghyuck Kim <janghyuck.kim@...sung.com>

A Closes: link will presumably help with the above info.  checkpatch
now warns about the absence of a Closes: