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Wysocki" Cc: akpm@linux-foundation.org, chrisl@kernel.org, kasong@tencent.com, pavel@kernel.org, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, baohua@kernel.org, usama.arif@linux.dev, linux-pm@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v6 3/3] PM: hibernate: fix spurious GFP mask WARNING in uswsusp path Message-ID: References: <20260320170313.163386-1-youngjun.park@lge.com> <20260320170313.163386-4-youngjun.park@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Stat-Signature: 5dgi9y8mcb5zax9fqxzpyiiz9t4kd99q X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: D708A180003 X-HE-Tag: 1774090133-494329 X-HE-Meta: U2FsdGVkX1/Om18faAx92zoziCXZC5MFvBMjMhldXp92lEIN7g1beAKVWTTEv0H7I8r8CWWcSPu1JxQYwABOTr31b2mF4BdJlJDLY1lrFpCWWbji9OCxP+hEvagGqQtNtrCtq3PUCYpLHEPlx+bk/RDC49vzKvCRUV5SzALdnbTLiPRW462ZgKzRC2WgBrAvBycDL32a9jE5GZwKwwvyE4ccICykHst0g2XHYYlLsR4dSIHkujsUNzm0bxknS02KTeQkxGkObZPRlWbt4ae576VMxkBurF2Au8ARQbBDRlHtycHoiMnN03mL//ZdsHgzKPLMBig+PSay7SQaH89IQJ9GvZypWsVFNSw+aWy3G0NN+sNHhkdZGcoF70tNmvNcy6GOM+EcnBv8C0CWPbtU1OyN6yYwgDdJp6FDESSaYOfEBi0rsnUKsP597iYA/j/EKCxKBq9kgQgqjFqny1d8BADPbJnAaANY7BuTtjlgSjapUNYVMMc9psRMDZItDOtTKFRnRDe54WHa547lIZ+QKm86c2iNIXSQs7Q+6GA33vPbsyqHny7zOI6dhVwOqNY98EWoKYeKL2SNWaTQvmlWq2vvWNA58n6pDuSiYXStpgl5oOI1BI9bQfHQtWz21jCIZ8+xbhziQxMzG9QA9IH/isU5msMe9CZkKe57QiviadxaihU6QKhs+nADe7gK1PWFxrhL8W9lgs2EeUSYQdcVxzyx3NiEeKcxUEj9y73nsgjbcYsfH4qnFhevmlbGmpnbeM1mibuIDRQzYmfNY2QQyN2KlZnJjOiufu8DPEVDRMwaid+/Di+t6LMrTvHqDb28N2F5845WRrvIKQJYCl0OAb23zN7XEU0At33H3u4tKWEh038qTPIb/v2rgODZNg6XnQsWI1z8JQIlz8ZOVkDaD4QL0A+KAe+NmAJbMQpD5Lbgr/6R1jvMwPlBhv/cIbmIV4NliuuM068gO+75jJt ZYq8CivR YOxU+3/x+VwNH7OSZ8yM6WjQJWM7w1tcrWRa8DBiZ3pBCSgcFtzpbGihYz541hDnC5md4xIaMLgBhDfKO5CiLzUMiPrXlW/HfoMH9B5RGGPMHnfHmaPqVKjQwCRlFlrtEQv8k6PQ6A2PrGsShKAKiaHZvriE9xcXa2TlaZp84NGRePbRNneYl45SmKDXPuyU3FGw5jvnVtKymrtU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Mar 20, 2026 at 07:20:24PM +0100, Rafael J. Wysocki wrote: >... Hi Rafael, Thanks for the review. Sorry for the back and forth on this one. I'm preparing to send the uswsusp GFP mask fix separately as you requested (with _nowarn rename and lockdep_assert_held). Before sending, I wanted to check on the approach. I originally found this WARNING while testing uswsusp and thought it was a localized issue. But AI review has kept uncovering more cases — first SNAPSHOT_FREEZE + snapshot_release(), and now dpm_resume_end() when dpm_prepare() fails. More callers than I expected use this defensive restore pattern. So I'd like your thoughts on the approach: 1. Introduce pm_restore_gfp_mask_nowarn() and update each caller. 2. Remove the WARN_ON from pm_restore_gfp_mask() itself, restoring the pre-stacking no-op behavior. I'm leaning towards option 2. Defensive restores are an established pattern in multiple paths, and warning against a legitimate no-op seems counterproductive — we'd just be playing whack-a-mole with _nowarn conversions as more callers turn up. What do you think? Youngjun Park