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Tue, 19 Aug 2025 21:55:33 -0700 (PDT) MIME-Version: 1.0 References: <20250819193404.46680-1-sj@kernel.org> In-Reply-To: From: Chris Li Date: Tue, 19 Aug 2025 21:55:22 -0700 X-Gmail-Original-Message-ID: X-Gm-Features: Ac12FXwHHeNsRxjdjpScCgLpGAs7xED92MNZ42-dt7hDOrZgQ0ynOsyqaYsS7XQ Message-ID: Subject: Re: [PATCH v4] mm/zswap: store Cc: Barry Song <21cnbao@gmail.com>, SeongJae Park , Andrew Morton , Chengming Zhou , Johannes Weiner , Nhat Pham , Yosry Ahmed , kernel-team@meta.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Takero Funaki , David Hildenbrand , Baoquan He , Kairui Song Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9C3A8140009 X-Stat-Signature: f6iq6d4e44z3jgopito67edj7nqmdun6 X-Rspam-User: X-HE-Tag: 1755665736-803549 X-HE-Meta: U2FsdGVkX19NVSCtUUSmq61oGl1VKa42k++7BJcejogSyX0hBvk/0eTKiynV+p+rHpttDA0C9Oh0ap4OgO9r66VCwgtrd3TrHujezoVOcXJrtM6h/8N3c7+AxvJSbnz0ZHYuRVqkp/jeN8AWTwcHpRDEAalbWjguYSaszAC9t2QoVy7pUIrDmUREg9apn8AVYOFNTOWEDJGt3ZqTHnlM127Tnol094AdpAJLpPjB66gYqG8/aKpdApBuuXbjBdxbR8wMw+o02jvWUMNqnjzMsI3kC0hjko2KfxT7qGE/ySaLQuSfIiRW1vO778jmFjtKYObMlLfnc8xm8LtTtj2iUUedvYnNCdguEAMGUYfSjERuAKwOb06CGKd9jarK5nWuqcoCSqdZzNaijEpuncaspLEJW7yA9JNaB41fQAhsMfmhz3EXtbx9dyRyAMf2iwsBZInj1U87DRK9OqjEU9800eop1a+wQYzhuucNQf9Oyqie2cfe7DayjZkYr8JByQEHn0cvDtVQzXuVvR2sXhtfcuFMn94uEYR0VtLm5/DItw+DKg3oak1rt7Q13IV7I8Be/NiEV/pDK3O4EaoYzYskqfcbHfQHwlcVxauBA7vA+uSPZIMIDmsAyPOAm7RlirYrZp/ri6GZvMotLsk1EBGEKHII2lePnyB5kbcLSzeP2abh1FCVyOPAiSSkGez2Oc2XMGiJM4/fbxRM5lCQhVxYgbEQ+xN5IJYu7o7b4VwnVyDErQv/DlEZAwv9yieka/FIyjdsJ8wSnapq8o8xt5GxsVuwXIRPxJ+uwpG7am4C6CyTokx3hTmpC5rfcUXXOEgeaF1dIMlwG/C2Wdsm0Xp7R57TxecoqxoItlkiHsETgObxcSiLGVXqCeMKOj8QgD0HHHoglbFxD6yqEf+pISeNEZ95ihYLWAzMNGY5eZIseSKAlViILYwtRKI+DKHIISO+92bFZ70JJIMmAjbm3aj JAED6B/Z nIBfPuYw7gpFxhc2sVHEfsbh/SkOv/UEwgl1q2Er9nRBJXhP+d96Mu16esOnqYxO/k5mQQ2WbEZ0n+Yb0V03u//rsRTPcWMFKqkvaOe81+TOQl9Rka5vzA98tNXJr5ZXfHnId8s2LL6oipB4zVu7tn/hzvzlBFaxZvzGS7SWNpAbROIu1d6YaW+xQZ3h7HxnHSc0Fre61WN0kGJoc3LgFOc73FWlK6XU26/tBvfFjwMAwzQVb8ziPUAhIusGGxCi8yQWq0Uv5K64SomhtpVN19I+1DZytlljYOq93rflTPXv2lYTMu3gl4/th2nKycoJFpg/XG6bfVylvrAW/tRbz/drYfMiv5CkT+Z+gFPWXxIPWdriK8xzK+hiUK2Uzy5x1vnS8x/an+lHHYto= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Aug 19, 2025 at 6:21=E2=80=AFPM Herbert Xu wrote: > > On Wed, Aug 20, 2025 at 01:13:13PM +1200, Barry Song wrote: > > > > Let=E2=80=99s sync with Herbert: have we reached the stage where all dr= ivers > > reliably return -ENOSPC when dst_buf is PAGE_SIZE but the compressed > > size would exceed it? > > It doesn't matter. Software compression should never fail, and > if it does fail due to a bug, that's not something that the user > of the API should worry about. > > Hardware compression should always fall back to software compression > in case of failure. > > IOW all compression errors should be treated as incompressible > data. In that case, you seem to suggest that the crypto library can NEVER return an error other than the dst buffer is too small. In that case I would suggest the crypto library remove that free form error return code. Just return true for success compression or false on failure. It is also strange to return a freeform error code and declare the caller shouldn't check on it. Ideally the caller shouldn't warn or bug on it, so it should handle the possible error other than -ENOSPC. Chris