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Fri, 09 Jan 2026 03:02:45 -0800 (PST) MIME-Version: 1.0 References: <20260106162200.2223655-1-smostafa@google.com> <20260106162200.2223655-4-smostafa@google.com> In-Reply-To: From: Mostafa Saleh Date: Fri, 9 Jan 2026 11:02:33 +0000 X-Gm-Features: AQt7F2oqTpF_L8hxvj3t4iE4ZAXrurkscrS9S6zaVPP7N-l_qQbRFrZajZBoJoU Message-ID: Subject: Re: [PATCH v5 3/4] iommu: debug-pagealloc: Track IOMMU pages To: Pranjal Shrivastava Cc: Baolu Lu , linux-mm@kvack.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, corbet@lwn.net, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, akpm@linux-foundation.org, vbabka@suse.cz, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, xiaqinxin@huawei.com, rdunlap@infradead.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: 4y5pz3fa3ddtn6dqs7mngu3rmrjtarre X-Rspamd-Queue-Id: CB6DEA0012 X-Rspamd-Server: rspam04 X-HE-Tag: 1767956566-985576 X-HE-Meta: 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 JHv5loDr w4HNh53cra4Yj/8Js59IHuZBCKd6bhvqaqMhB/Npm/GLHVEdkQHSC6FQcmDrU+B2Anxxg8I1nuR7nlR7BEA06jtBqSnPvtYE7ZshaQZVLOHJ1YPKjrW06o6AVmeFvQJhAFOAY1bGOiUhPlqXGmG4D4GajM2KSfh7as3fLfiG1atY9rye2rSXeuiFr72Gj+tBIOb0Gkhqf95ykeTySkI2mOqsT82ikKjPq2dgHCRPFZuwqZmVktbjpIkWugjV/6ANc5j5UcEE4wLDQZ68= X-Bogosity: Ham, tests=bogofilter, spamicity=0.009233, 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 9, 2026 at 7:34=E2=80=AFAM Pranjal Shrivastava wrote: > > On Fri, Jan 09, 2026 at 11:28:32AM +0800, Baolu Lu wrote: > > On 1/8/26 19:33, Mostafa Saleh wrote: > > > I have this, it should have the same effect + a WARN, I will include > > > it in the new version > > > > > > diff --git a/drivers/iommu/iommu-debug-pagealloc.c > > > b/drivers/iommu/iommu-debug-pagealloc.c > > > index 5353417e64f9..64ec0795fe4c 100644 > > > --- a/drivers/iommu/iommu-debug-pagealloc.c > > > +++ b/drivers/iommu/iommu-debug-pagealloc.c > > > @@ -146,16 +146,12 @@ void __iommu_debug_unmap_end(struct iommu_domai= n *domain, > > > if (unmapped =3D=3D size) > > > return; > > > > > > - /* > > > - * If unmap failed, re-increment the refcount, but if it unma= pped > > > - * larger size, decrement the extra part. > > > - */ > > > + /* If unmap failed, re-increment the refcount. */ > > > if (unmapped < size) > > > __iommu_debug_update_iova(domain, iova + unmapped, > > > size - unmapped, true); > > > else > > > - __iommu_debug_update_iova(domain, iova + size, > > > - unmapped - size, false); > > > + WARN_ONCE(1, "iommu: unmap larger than requested is > > > not supported in debug_pagealloc\n"); > > > } > > > > > > void iommu_debug_init(void) > > > > How aobut > > > > if ((unmapped =3D=3D size) || WARN_ON_ONCE(unmapped > size)) > > return; > > > > /* If unmap failed, re-increment the refcount. */ > > __iommu_debug_update_iova(domain, iova + unmapped, size - unmappe= d, true); > > > > ? > > > > That's nice, We could also print the message as Mostafa mentioned, like: > > if ((unmapped =3D=3D size) || WARN_ON_ONCE(unmapped > size, > "iommu: unmap larger than requested is not supported in > debug_pagealloc\n")) > > An explicit "This is unsupported" warning makes it clear IMHO. > If a driver triggers this, at least we know the sanitizer state isn't > supported. > I guess both are fine, the WARN points to the line which should be simple to deduce the cause anyway. Thanks, Mostafa > Thanks, > Praan