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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769088945; bh=wED3dXV0kHkiBnPWNUBgYlSUdtgP2fArJ/kzjZEMltI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=mrM43KnIhyHDnc8ivUCX5HTrM9Pl42GBN8gXbejQ3Jl7OGoZ6s6TYv7Q9f+Ds41mV +atyWBT9K1XOmZr0pF5xVDisRvZ3G+sA0qlf+8xqzuMhEvZp4UEln1+29gf3zF8UIM hDr0aYGQEDqiPxMYnxspQa3y7BzZqMUsjuoGrP0jIAK+PgK0D2VLGCIn2k5S95TWLs uieNDly2PL9lHs2HFOjsXJgRHIrcw5486a5jYlh+T2wfAUhDov1hXXSAUo6cTbh/uZ yD8mWEN/VEDP5hyMTo/uckvNJclqUK7clMtEpzkS9kYenRw3CDQY2ZRB1Qh1ai61Ql pXhD2DGjTqOBQ== From: Pratyush Yadav To: ranxiaokai627@163.com Cc: pratyush@kernel.org, surenb@google.com, akpm@linux-foundation.org, pasha.tatashin@soleen.com, kent.overstreet@linux.dev, rppt@kernel.org, graf@amazon.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, ran.xiaokai@zte.com.cn, stable@vger.kernel.org Subject: Re: [PATCH RESEND v3] kho: init alloc tags when restoring pages from reserved memory In-Reply-To: <20260122132740.176468-1-ranxiaokai627@163.com> (ranxiaokai's message of "Thu, 22 Jan 2026 13:27:40 +0000") References: <20260122132740.176468-1-ranxiaokai627@163.com> Date: Thu, 22 Jan 2026 14:35:41 +0100 Message-ID: <2vxzcy31bwia.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: D9ED01A000E X-Stat-Signature: nb45yjgjc654sbomy7oc9idpj5ep9ig3 X-HE-Tag: 1769088945-162528 X-HE-Meta: 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 aEumlbTm n/Djk2ghZXVYFlkm8qXVroLpNFwqVTL3RdU2hYP5y44hwmF5nlygv356Z6o1R65j+a3YAxa8y9GS+Mv77kUxkspep9R29N5d6lL4kisB9l2/+zzMmIVj0SRNTHXcc6OpStd7LLm+aiir5qXbCMZbllGzFunoVDKWxJwrBsw+uDbV96Dr4fkGmVpLkc/3GYVjdIov2qQNsdMQBFfoZKwJ5V+MExPAMxoedagK4OKRltwaKI9Sar8/vmyHMcV/DAXzHVLiXZkvZfYyWZO3D/702XRT8sg== 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 Thu, Jan 22 2026, ranxiaokai627@163.com wrote: > From: Ran Xiaokai > > Memblock pages (including reserved memory) should have their allocation > tags initialized to CODETAG_EMPTY via clear_page_tag_ref() before being > released to the page allocator. When kho restores pages through > kho_restore_page(), missing this call causes mismatched > allocation/deallocation tracking and below warning message: > > alloc_tag was not set > WARNING: include/linux/alloc_tag.h:164 at ___free_pages+0xb8/0x260, CPU#1: swapper/0/1 > RIP: 0010:___free_pages+0xb8/0x260 > kho_restore_vmalloc+0x187/0x2e0 > kho_test_init+0x3c4/0xa30 > do_one_initcall+0x62/0x2b0 > kernel_init_freeable+0x25b/0x480 > kernel_init+0x1a/0x1c0 > ret_from_fork+0x2d1/0x360 > > Add missing clear_page_tag_ref() annotation in kho_restore_page() to > fix this. > > Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation") > Cc: > Signed-off-by: Ran Xiaokai > --- > > v2 -> v3: > - also call clear_page_tag_ref() for non-compound order-0 tail pages > > kernel/liveupdate/kexec_handover.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c > index d4482b6e3cae..96767b106cac 100644 > --- a/kernel/liveupdate/kexec_handover.c > +++ b/kernel/liveupdate/kexec_handover.c > @@ -255,6 +255,14 @@ static struct page *kho_restore_page(phys_addr_t phys, bool is_folio) > if (is_folio && info.order) > prep_compound_page(page, info.order); > > + /* Always mark headpage's codetag as empty to avoid accounting mismatch */ > + clear_page_tag_ref(page); > + if (!is_folio) { > + /* Also do that for the non-compound tail pages */ > + for (unsigned int i = 1; i < nr_pages; i++) > + clear_page_tag_ref(page + i); > + } > + I think it would be a little bit better if we just did this in the loop above instead of looping again. But I think it is fine for now. I can fix it up in the next release. Reviewed-by: Pratyush Yadav > adjust_managed_page_count(page, nr_pages); > return page; > } -- Regards, Pratyush Yadav