From: Baolin Wang <baolin.wang@linux.alibaba.com>
To: Shivank Garg <shivankg@amd.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>,
"Liam R . Howlett" <Liam.Howlett@oracle.com>,
Nico Pache <npache@redhat.com>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Zach O'Keefe <zokeefe@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org,
Branden Moore <Branden.Moore@amd.com>
Subject: Re: [PATCH V3 1/2] mm/khugepaged: map dirty/writeback pages failures to EAGAIN
Date: Tue, 2 Dec 2025 15:56:40 +0800 [thread overview]
Message-ID: <c91f8c76-ca5a-4e8c-84a4-1b91b150e202@linux.alibaba.com> (raw)
In-Reply-To: <20251201185604.210634-8-shivankg@amd.com>
On 2025/12/2 02:56, Shivank Garg wrote:
> When collapse_file encounters dirty or writeback pages in file-backed
> mappings, it currently returns SCAN_FAIL which maps to -EINVAL. This is
> misleading as EINVAL suggests invalid arguments, whereas dirty/writeback
> pages represent transient conditions that may resolve on retry.
>
> Introduce SCAN_PAGE_DIRTY_OR_WRITEBACK to cover both dirty and writeback
> states, mapping it to -EAGAIN. For MADV_COLLAPSE, this provides userspace
> with a clear signal that retry may succeed after writeback completes.
> For khugepaged, this is harmless as it will naturally revisit the range
> during periodic scans after async writeback completes.
>
> Reported-by: Branden Moore <Branden.Moore@amd.com>
> Closes: https://lore.kernel.org/all/4e26fe5e-7374-467c-a333-9dd48f85d7cc@amd.com
> Fixes: 34488399fa08 ("mm/madvise: add file and shmem support to MADV_COLLAPSE")
> Reviewed-by: Dev Jain <dev.jain@arm.com>
> Reviewed-by: Lance Yang <lance.yang@linux.dev>
> Signed-off-by: Shivank Garg <shivankg@amd.com>
> ---
LGTM.
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
next prev parent reply other threads:[~2025-12-02 7:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-01 18:56 [PATCH V3 0/2] mm/khugepaged: fix dirty page handling for MADV_COLLAPSE Shivank Garg
2025-12-01 18:56 ` [PATCH V3 1/2] mm/khugepaged: map dirty/writeback pages failures to EAGAIN Shivank Garg
2025-12-02 7:56 ` Baolin Wang [this message]
2025-12-04 1:54 ` wang lian
2025-12-01 18:56 ` [PATCH V3 2/2] mm/khugepaged: retry with sync writeback for MADV_COLLAPSE Shivank Garg
2025-12-02 4:50 ` Lance Yang
2025-12-03 18:25 ` Garg, Shivank
2025-12-04 6:53 ` Lance Yang
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