From: Andrew Morton <akpm@linux-foundation.org>
To: Hongfu Li <hongfu.li@linux.dev>
Cc: hughd@google.com, baolin.wang@linux.alibaba.com,
vivek.kasireddy@intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Hongfu Li <lihongfu@kylinos.cn>
Subject: Re: [PATCH] mm/memfd: don't unreserve hugetlb pages on -EEXIST in error path
Date: Mon, 31 Aug 2026 17:35:13 -0700 [thread overview]
Message-ID: <20260831173513.41184f1d27cd83f2c8f9b935@linux-foundation.org> (raw)
In-Reply-To: <20260831090631.29227-1-hongfu.li@linux.dev>
On Mon, 31 Aug 2026 17:06:31 +0800 Hongfu Li <hongfu.li@linux.dev> wrote:
> From: Hongfu Li <lihongfu@kylinos.cn>
>
> If hugetlb_add_to_page_cache() fails with -EEXIST, a concurrent fault has
> already instantiated the folio in the page cache, and the reservation now
> belongs to that folio. Calling hugetlb_unreserve_pages() in that case
> incorrectly removes the region backing the cached folio, and a later
> truncate or inode eviction passes a negative (chg - freed) into
> hugepage_subpool_put_pages(), corrupting subpool and resv_huge_pages
> accounting.
>
> Skip the unreserve on -EEXIST; failures other than -EEXIST leave the
> reservation unconsumed and still unreserve it.
Thanks.
AI review might have found another bug and it suggests that your
proposal only partially fixes this bug:
https://sashiko.dev/#/patchset/20260831090631.29227-1-hongfu.li@linux.dev
next prev parent reply other threads:[~2026-09-01 0:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-31 9:06 Hongfu Li
2026-09-01 0:35 ` Andrew Morton [this message]
2026-09-01 9:01 ` Hongfu Li
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