From: Heiko Carstens <hca@linux.ibm.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>,
kvm@vger.kernel.org, linux-s390@vger.kernel.org,
frankja@linux.ibm.com, nsg@linux.ibm.com, nrb@linux.ibm.com,
seiden@linux.ibm.com, schlameuss@linux.ibm.com,
svens@linux.ibm.com, agordeev@linux.ibm.com, david@redhat.com,
gerald.schaefer@linux.ibm.com
Subject: Re: [PATCH v2 08/20] KVM: s390: KVM page table management functions: allocation
Date: Tue, 16 Sep 2025 19:36:44 +0200 [thread overview]
Message-ID: <20250916173644.27229Kcc-hca@linux.ibm.com> (raw)
In-Reply-To: <15f451d9-ecb3-4a82-9b9a-2de64b93944d@de.ibm.com>
On Tue, Sep 16, 2025 at 07:06:06PM +0200, Christian Borntraeger wrote:
>
> Am 16.09.25 um 19:05 schrieb Claudio Imbrenda:
>
> > > > I think GFP_ATOMIC actually gives more guarantees?
> > >
> > > In real life GFP_ATOMIC can fail, GFP_KERNEL does not.All gfp allocation failures
> > > are usually the atomic ones.
> >
> > interesting... then I guess I need GFP_KERNEL | GFP_ATOMIC ?
>
> No. ATOMIC always means: can fail.
So GFP_KERNEL alone is what is needed here. It is undocumented that
small GFP_KERNEL allocations will never fail (retried for ever):
https://lwn.net/Articles/627419/
https://lwn.net/Articles/723317/
While GFP_ATOMIC will fail e.g. if I/O is required to free up some
memory.
next prev parent reply other threads:[~2025-09-16 17:36 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-10 18:07 [PATCH v2 00/20] KVM: s390: gmap rewrite, the real deal Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 01/20] KVM: s390: add P bit in table entry bitfields, move union vaddress Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 02/20] s390: Move sske_frame() to a header Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 03/20] KVM: s390: Add gmap_helper_set_unused() Claudio Imbrenda
2025-09-11 8:38 ` Nico Boehr
2025-09-12 9:17 ` Nina Schoetterl-Glausch
2025-09-15 11:33 ` Claudio Imbrenda
2025-10-27 18:00 ` Nina Schoetterl-Glausch
2025-09-10 18:07 ` [PATCH v2 04/20] KVM: s390: Enable KVM_GENERIC_MMU_NOTIFIER Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 05/20] KVM: s390: Add helper functions for fault handling Claudio Imbrenda
2025-09-12 17:56 ` Nina Schoetterl-Glausch
2025-09-15 11:49 ` Claudio Imbrenda
2025-09-18 14:19 ` Alexander Gordeev
2025-09-18 14:46 ` Claudio Imbrenda
2025-09-18 14:41 ` Alexander Gordeev
2025-09-18 15:10 ` Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 06/20] KVM: s390: Rename some functions in gaccess.c Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 07/20] KVM: s390: KVM-specific bitfields and helper functions Claudio Imbrenda
2025-09-17 12:18 ` Heiko Carstens
2025-09-17 12:51 ` Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 08/20] KVM: s390: KVM page table management functions: allocation Claudio Imbrenda
2025-09-11 8:22 ` Janosch Frank
2025-09-11 8:43 ` Claudio Imbrenda
2025-09-16 16:26 ` Heiko Carstens
2025-09-16 16:47 ` Claudio Imbrenda
2025-09-16 17:01 ` Christian Borntraeger
2025-09-16 17:05 ` Claudio Imbrenda
2025-09-16 17:06 ` Christian Borntraeger
2025-09-16 17:36 ` Heiko Carstens [this message]
2025-09-17 7:27 ` Heiko Carstens
2025-09-17 11:25 ` Claudio Imbrenda
2025-09-17 12:30 ` Heiko Carstens
2025-09-17 13:11 ` Claudio Imbrenda
2025-09-17 13:26 ` Christian Borntraeger
2025-09-17 14:00 ` Claudio Imbrenda
2025-09-17 14:05 ` Christian Borntraeger
2025-09-17 14:11 ` Claudio Imbrenda
2025-09-17 17:08 ` Claudio Imbrenda
2025-09-17 13:31 ` Heiko Carstens
2025-09-17 14:00 ` Claudio Imbrenda
2025-09-17 12:12 ` Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 09/20] KVM: s390: KVM page table management functions: clear and replace Claudio Imbrenda
2025-09-11 12:57 ` Janosch Frank
2025-09-11 13:19 ` Claudio Imbrenda
2025-09-11 13:27 ` Janosch Frank
2025-09-16 15:56 ` Heiko Carstens
2025-09-16 16:47 ` Heiko Carstens
2025-09-16 17:04 ` Claudio Imbrenda
2025-09-16 17:27 ` Heiko Carstens
2025-09-10 18:07 ` [PATCH v2 10/20] KVM: s390: KVM page table management functions: walks Claudio Imbrenda
2025-09-11 12:56 ` Janosch Frank
2025-09-11 13:14 ` Claudio Imbrenda
2025-09-12 5:47 ` Gerd Bayer
2025-09-16 16:22 ` Heiko Carstens
2025-09-16 16:48 ` Claudio Imbrenda
2025-09-16 17:24 ` Heiko Carstens
2025-09-17 11:14 ` Claudio Imbrenda
2025-09-17 12:55 ` Heiko Carstens
2025-09-17 13:13 ` Claudio Imbrenda
2025-09-17 13:24 ` Heiko Carstens
2025-09-17 14:01 ` Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 11/20] KVM: s390: KVM page table management functions: storage keys Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 12/20] KVM: s390: KVM page table management functions: lifecycle management Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 13/20] KVM: s390: KVM page table management functions: CMMA Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 14/20] KVM: s390: New gmap code Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 15/20] KVM: s390: Stop using CONFIG_PGSTE Claudio Imbrenda
2025-09-16 7:45 ` Steffen Eiden
2025-09-10 18:07 ` [PATCH v2 16/20] KVM: s390: Switch to new gmap Claudio Imbrenda
2025-09-17 13:20 ` Heiko Carstens
2025-09-10 18:07 ` [PATCH v2 17/20] KVM: s390: Remove gmap from s390/mm Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 18/20] KVM: S390: Remove PGSTE code from linux/s390 mm Claudio Imbrenda
2025-09-16 7:30 ` Steffen Eiden
2025-09-16 9:24 ` Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 19/20] KVM: s390: Enable 1M pages for gmap Claudio Imbrenda
2025-09-10 18:07 ` [PATCH v2 20/20] KVM: s390: Storage key manipulation IOCTL Claudio Imbrenda
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