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

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Message-Id: <20250409140848.da67768ac1f5e79d7296de4d@linux-foundation.org>
Date: Wed, 9 Apr 2025 14:08:48 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: "T.J. Mercier" <tjmercier@...gle.com>
Cc: 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 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.