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Thu, 22 Jan 2026 11:48:55 -0800 (PST) MIME-Version: 1.0 References: <20260116165416.1262531-1-pratyush@kernel.org> In-Reply-To: <20260116165416.1262531-1-pratyush@kernel.org> From: Samiullah Khawaja Date: Thu, 22 Jan 2026 11:48:44 -0800 X-Gm-Features: AZwV_QgYYDLmHCzfY5_3eVms8MoiUtOZs2iFbsinPGV_5oYeZSyGGaB4IQhOzrs Message-ID: Subject: Re: [PATCH] kho: print which scratch buffer failed to be reserved To: Pratyush Yadav Cc: Andrew Morton , Alexander Graf , Mike Rapoport , Pasha Tatashin , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Matlack , Jason Miu Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 487891C0007 X-Stat-Signature: yq8cgj9kskmh81rpi4ua6q6fedeea13i X-Rspam-User: X-HE-Tag: 1769111337-849497 X-HE-Meta: U2FsdGVkX1/uDjNkIGJiGvfUzKE7iTsbzONJvh1hUt81K5gZEBsIXO9nn/6ZN6vh0b6RCdc9T5p8sTznGmT2tNrQtTZDoFJCgduD5gm5Py4C5l3E7ppK/+OYFScWH5sxCSsV0l2ytTGbPgq7jmAAc8mA+jGT/g1HOjdvu8yRoXIeSVaWGg1KeXJjLN1eAM/hDyJyZD9b216W/ivzayaz5p6Xjp0XP6XH3I5wVow5NXNhxXxhcCq+rnisNAhpSLbMo6gBkL+1tykzizEVwEfdWRDGk8Fn/KuOMYaGhkOWuIU0yVG6ngRvUCPo+BjIy88qheXnsCV7ZlaA46GvFE90EDFiwy7mqCPsvPQKNacbjUHRsmXuD9QWUhdTa4irmmFkhR9arkPa4F0jpMOVh38yudGYBZbXSbuqnJtRtHwYR1/C91Ojo9nZaXnzCCn/VJxuins5GP60nWUGPCgskJHFDX4lpG1mF2Zon0LnzeQizQJmWkuuKuc5tepJq1r3q//p9E4dn5o6TL2XqtBj/knG2khccXyYpgZTYm/b/DdiDPcOMiODSOuhbL5zPZlglfinFJ9NSmL9rNKJrktyMtfHnFtcFj1A/DgsNPu6tnnEsjzG0srDe4Rgv7G9u+qCEdMnfBoyROwJuWQmdx3kixoTvvv/B+sYXT0IAj4WFalz8aREJkBAtebv5QYvPhdbdPixguWWtsdoXdKNkjJB06/EkintGofA3cQUF5bhzJug0u8S9imTEmzRTGQ3yaXhFcr80CKEJw5wgcRcjxOKOFJZX5VFmNsMjFkpMn50LsJF/1tmptOi8C7+55QalN6kmK73lhpa6DkoqfH8y3vOeP5p4NsLYRtJ79SBNcjpaJ8rT31D6B2WvJvn35Olo/UoxgvNxYiobdbUW1r+ZdrUylINJWfZ0GU2j3ULFgtq1rrpVeo/fLIZ7IBycQofMRG1nr22EswJY2sJIwHUHUgy79z OAP6C1/0 l8tIaD6IwRFw6HFqxm9y2d6gGOkxqaR6fq+2noTScchCpWOh4XSBv7q3KK6D0rBmBxfpeIMZvpnNI/8KoMF+PK0NW5gGQF4Q/LxorvLR4RnPbfxXW6REmqX994jXkxFnj909d8tRQfAoQfT69o/sDAsyoeGaY6y1chXNjpCC94esqTgyNTKecWNdhQlvgzeS+YvEQz6Z2htNo68CB9xY0nBHGOHsY0RtejSgvSEVFsjd/FtMr99kVYcCDwwGhbF5xanrJqLqh/KD5YMEfbEu6gKJ2z0F90c6fn3e0 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 Fri, Jan 16, 2026 at 8:54=E2=80=AFAM Pratyush Yadav wrote: > > From: "Pratyush Yadav (Google)" > > When scratch area fails to reserve, KHO prints a message indicating > that. But it doesn't say which scratch failed to allocate. This can be > useful information for debugging. Even more so when the failure is hard > to reproduce. > > Along with the current message, also print which exact scratch area > failed to be reserved. > > Signed-off-by: Pratyush Yadav (Google) > --- > kernel/liveupdate/kexec_handover.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec= _handover.c > index 49bf2cecab12..636bd96780ae 100644 > --- a/kernel/liveupdate/kexec_handover.c > +++ b/kernel/liveupdate/kexec_handover.c > @@ -651,8 +651,10 @@ static void __init kho_reserve_scratch(void) > kho_scratch_cnt =3D num_online_nodes() + 2; > size =3D kho_scratch_cnt * sizeof(*kho_scratch); > kho_scratch =3D memblock_alloc(size, PAGE_SIZE); > - if (!kho_scratch) > + if (!kho_scratch) { > + pr_err("Failed to reserve scratch array\n"); > goto err_disable_kho; > + } > > /* > * reserve scratch area in low memory for lowmem allocations in t= he > @@ -661,8 +663,10 @@ static void __init kho_reserve_scratch(void) > size =3D scratch_size_lowmem; > addr =3D memblock_phys_alloc_range(size, CMA_MIN_ALIGNMENT_BYTES,= 0, > ARCH_LOW_ADDRESS_LIMIT); > - if (!addr) > + if (!addr) { > + pr_err("Failed to reserve lowmem scratch buffer\n"); > goto err_free_scratch_desc; > + } > > kho_scratch[i].addr =3D addr; > kho_scratch[i].size =3D size; > @@ -671,8 +675,10 @@ static void __init kho_reserve_scratch(void) > /* reserve large contiguous area for allocations without nid */ > size =3D scratch_size_global; > addr =3D memblock_phys_alloc(size, CMA_MIN_ALIGNMENT_BYTES); > - if (!addr) > + if (!addr) { > + pr_err("Failed to reserve global scratch buffer\n"); > goto err_free_scratch_areas; > + } > > kho_scratch[i].addr =3D addr; > kho_scratch[i].size =3D size; > @@ -683,8 +689,10 @@ static void __init kho_reserve_scratch(void) > addr =3D memblock_alloc_range_nid(size, CMA_MIN_ALIGNMENT= _BYTES, > 0, MEMBLOCK_ALLOC_ACCESSI= BLE, > nid, true); > - if (!addr) > + if (!addr) { > + pr_err("Failed to reserve nid %d scratch buffer\n= ", nid); > goto err_free_scratch_areas; > + } > > kho_scratch[i].addr =3D addr; > kho_scratch[i].size =3D size; > > base-commit: c37fac0551448c68e36f14782acaf662c7a1775e > -- > 2.52.0.457.g6b5491de43-goog > Reviewed-by: Samiullah Khawaja Tested-by: Samiullah Khawaja Tested on my test machine while investigating the scratch space allocation failure.