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AJvYcCVj5Ja1ytcVQT+EDNq245pqnJPXbVaXAMFMDGMJx/TdeYdipRSYaLrG4D27Ia8C8HBXmsnysjKOgw==@kvack.org X-Gm-Message-State: AOJu0YzOb6+onEjsM4u1xY1oFZ9OEYljscVAcTWtR5j3SIizSTDUnPaq sn5odBPqUMKt7OFIrPtr1WcEtOqSCSS47D6gQ+/tPu6GetSb5bmosApI/i1QUNSb16Sptis7rI7 o0sBcxOyXr04+fZFAbcRqY3/v66Q3WvPSHqSIRTFaOA== X-Gm-Gg: AY/fxX55iQEiQxHAdW6VxH950FcC0w7lwJQjqyzhGAHKmURnBbgWenQopXj4dYMgoeS fPSOMFGsxOuADZIFS02B+rpyBwr3lMw/SIfk9IwnEwCIqCDc0FVFYxLOgQucH9Ul9Wy1AtMI63z ILVoPFXXRHzqQ2PYW+ztQzxDAmEuAF+nHwgtKCuf2dpcKs9P66+dOq4ekEeXoTK971B2QfCFruc lo73m15VQmKXThco7ABW9d9YAlGQQovlGTzED/3CXZjMrSRf/HBlf1KE9+KrQ1mx2gQlG6KEz6f HXl3HlZ9bI1V2yMlAoj1Ay5Ixw== X-Google-Smtp-Source: AGHT+IGMZWTrRNb+slpZu2y8eWg+j4WfA9NxSt2fzIC0sx/x8C1VBQ1abXUUHhx62KZhGghaGNGmSmYa9XlRYAPUmTg= X-Received: by 2002:a05:6402:3587:b0:64d:3b22:a5b9 with SMTP id 4fb4d7f45d1cf-64d3b22a88fmr23190814a12.9.1767107167449; Tue, 30 Dec 2025 07:06:07 -0800 (PST) MIME-Version: 1.0 References: <7024cefd-bf27-430b-b8fa-04e1457e0eb8@proton.me> <86zf718072.fsf@kernel.org> In-Reply-To: <86zf718072.fsf@kernel.org> From: Pasha Tatashin Date: Tue, 30 Dec 2025 10:05:28 -0500 X-Gm-Features: AQt7F2qJ3a7s5qfdbisEUB9bUzL_h2Hb6hCdpCgwLMjci1CkKVcHCaWGzaNSb2I Message-ID: Subject: Re: [PATCH] kho: add support for deferred struct page init To: Pratyush Yadav Cc: Fadouse , Evangelos Petrongonas , Mike Rapoport , Alexander Graf , Andrew Morton , Jason Miu , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, nh-open-source@amazon.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: E52CA140018 X-Stat-Signature: zqmyzfm6dzfgznnkjs6etx1iy73cupji X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1767107168-798512 X-HE-Meta: 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 yWjQI4DD 5g+zrCA+/ohV/qyBooR6/WfGUVgAubBG9iUQABFaS6CMa09blXc/WpqZ9B4Osi2FVseml9lkSiWPzxykHNo/Us6wIpaU0/W4FJut3XhuP+IJ/8Eb9/cbdDqek4nMvQk4dyKxP++8xSWNXksgEkC3nJVCgh5GnA8oreB5//pgvP5R4VxkFC7KOhbPjPnIMCj3tshWx8v4zY9Y7TzpL69SJT++OO+ApUprR3j7ClUumIoIblUtwyOR46e9y9g== 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 Mon, Dec 29, 2025 at 4:09=E2=80=AFPM Pratyush Yadav wrote: > > On Wed, Dec 24 2025, Fadouse wrote: > > > Hi Evangelos, Mike, Pasha, Pratyush, > > > > I independently hit a crash in the LUO/memfd restore path with > > CONFIG_DEFERRED_STRUCT_PAGE_INIT=3Dy, on a local build based on dd9b004= b7ff3 > > (x86_64 QEMU, 6.19.0-rc1 timeframe). > > How? config KEXEC_HANDOVER depends on !DEFERRED_STRUCT_PAGE_INIT. So you > shouldn't even be able to enable KHO or LUO with > CONFIG_DEFERRED_STRUCT_PAGE_INIT=3Dy. Are you sure it is enabled? I think, Fadouse reported a bug with this patch applied, not an upstream bu= g. Pasha > > > > > In my reproducer, stage1 preserves a memfd via LUO and kexecs into stag= e2; > > stage2 calls LIVEUPDATE_SESSION_FINISH without retrieving files. I obse= rved > > a reliable crash in adjust_managed_page_count() from kho_restore_page()= . > > > > Minimal excerpt: > > > > stage2: start > > stage2: retrieved session fd=3D4 > > BUG: unable to handle page fault for address: 0000000000001410 > > RIP: adjust_managed_page_count+0x29/0x40 > > Call Trace: > > kho_restore_page+0x18a/0x1c0 > > kho_restore_folio+0xe/0x60 > > memfd_luo_finish+0xe6/0x160 > > luo_file_finish+0x188/0x240 > > luo_session_finish+0x2c/0x80 > > luo_session_ioctl+0xf5/0x170 > > __x64_sys_ioctl+0x91/0xe0 > > > > Applying the patch in <20251216084913.86342-1-epetron@amazon.de> makes = the > > issue no longer reproduce for me. > > > > I can share full logs and the small two-stage initramfs reproducer if n= eeded. > > > > Thanks, > > YanXin Li > > > > Tested-by: YanXin Li > > > [...] > > -- > Regards, > Pratyush Yadav