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Tsirkin" , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Maxime Coquelin X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 9185912001D X-Stat-Signature: dptsz7or8wuy8jx6ahhzmhoebs8b3gs4 X-Rspam-User: X-HE-Tag: 1722479496-630898 X-HE-Meta: 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 IqdEe7wf 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 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 Wed, Jul 31, 2024 at 1:05=E2=80=AFPM Barry Song <21cnbao@gmail.com> wrot= e: > > On Wed, Jul 31, 2024 at 12:13=E2=80=AFPM Jason Wang = wrote: > > > > On Wed, Jul 31, 2024 at 12:12=E2=80=AFPM Barry Song <21cnbao@gmail.com>= wrote: > > > > > > On Wed, Jul 31, 2024 at 11:58=E2=80=AFAM Jason Wang wrote: > > > > > > > > On Wed, Jul 31, 2024 at 11:15=E2=80=AFAM Barry Song <21cnbao@gmail.= com> wrote: > > > > > > > > > > On Wed, Jul 31, 2024 at 11:10=E2=80=AFAM Jason Wang wrote: > > > > > > > > > > > > On Wed, Jul 31, 2024 at 8:03=E2=80=AFAM Barry Song <21cnbao@gma= il.com> wrote: > > > > > > > > > > > > > > From: Barry Song > > > > > > > > > > > > > > mm doesn't support non-blockable __GFP_NOFAIL allocation. Bec= ause > > > > > > > __GFP_NOFAIL without direct reclamation may just result in a = busy > > > > > > > loop within non-sleepable contexts. > > > > > > > > > > > > > > static inline struct page * > > > > > > > __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > > > > > > > struct alloc_= context *ac) > > > > > > > { > > > > > > > ... > > > > > > > /* > > > > > > > * Make sure that __GFP_NOFAIL request doesn't leak o= ut and make sure > > > > > > > * we always retry > > > > > > > */ > > > > > > > if (gfp_mask & __GFP_NOFAIL) { > > > > > > > /* > > > > > > > * All existing users of the __GFP_NOFAIL are= blockable, so warn > > > > > > > * of any new users that actually require GFP= _NOWAIT > > > > > > > */ > > > > > > > if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp= _mask)) > > > > > > > goto fail; > > > > > > > ... > > > > > > > } > > > > > > > ... > > > > > > > fail: > > > > > > > warn_alloc(gfp_mask, ac->nodemask, > > > > > > > "page allocation failure: order:%u", = order); > > > > > > > got_pg: > > > > > > > return page; > > > > > > > } > > > > > > > > > > > > > > Let's move the memory allocation out of the atomic context an= d use > > > > > > > the normal sleepable context to get pages. > > > > > > > > > > > > > > [RFT]: This has only been compile-tested; I'd prefer if the V= DPA maintainers > > > > > > > handles it. > > > > > > > > > > > > > > Cc: "Michael S. Tsirkin" > > > > > > > Cc: Jason Wang > > > > > > > Cc: Xuan Zhuo > > > > > > > Cc: "Eugenio P=C3=A9rez" > > > > > > > Cc: Maxime Coquelin > > > > > > > Signed-off-by: Barry Song > > > > > > > --- > > > > > > > drivers/vdpa/vdpa_user/iova_domain.c | 31 ++++++++++++++++++= +++++----- > > > > > > > drivers/vdpa/vdpa_user/iova_domain.h | 5 ++++- > > > > > > > drivers/vdpa/vdpa_user/vduse_dev.c | 4 +++- > > > > > > > 3 files changed, 33 insertions(+), 7 deletions(-) > > > > > > > > > > > > > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/v= dpa/vdpa_user/iova_domain.c > > > > > > > index 791d38d6284c..9318f059a8b5 100644 > > > > > > > --- a/drivers/vdpa/vdpa_user/iova_domain.c > > > > > > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c > > > > > > > @@ -283,7 +283,23 @@ int vduse_domain_add_user_bounce_pages(s= truct vduse_iova_domain *domain, > > > > > > > return ret; > > > > > > > } > > > > > > > > > > > > > > -void vduse_domain_remove_user_bounce_pages(struct vduse_iova= _domain *domain) > > > > > > > +struct page **vduse_domain_alloc_pages_to_remove_bounce(stru= ct vduse_iova_domain *domain) > > > > > > > +{ > > > > > > > + struct page **pages; > > > > > > > + unsigned long count, i; > > > > > > > + > > > > > > > + if (!domain->user_bounce_pages) > > > > > > > + return NULL; > > > > > > > + > > > > > > > + count =3D domain->bounce_size >> PAGE_SHIFT; > > > > > > > + pages =3D kmalloc_array(count, sizeof(*pages), GFP_KE= RNEL | __GFP_NOFAIL); > > > > > > > + for (i =3D 0; i < count; i++) > > > > > > > + pages[i] =3D alloc_page(GFP_KERNEL | __GFP_NO= FAIL); > > > > > > > + > > > > > > > + return pages; > > > > > > > +} > > > > > > > + > > > > > > > +void vduse_domain_remove_user_bounce_pages(struct vduse_iova= _domain *domain, struct page **pages) > > > > > > > { > > > > > > > struct vduse_bounce_map *map; > > > > > > > unsigned long i, count; > > > > > > > @@ -294,15 +310,16 @@ void vduse_domain_remove_user_bounce_pa= ges(struct vduse_iova_domain *domain) > > > > > > > > > > > > > > count =3D domain->bounce_size >> PAGE_SHIFT; > > > > > > > for (i =3D 0; i < count; i++) { > > > > > > > - struct page *page =3D NULL; > > > > > > > + struct page *page =3D pages[i]; > > > > > > > > > > > > > > map =3D &domain->bounce_maps[i]; > > > > > > > - if (WARN_ON(!map->bounce_page)) > > > > > > > + if (WARN_ON(!map->bounce_page)) { > > > > > > > + put_page(page); > > > > > > > continue; > > > > > > > + } > > > > > > > > > > > > > > /* Copy user page to kernel page if it's in u= se */ > > > > > > > if (map->orig_phys !=3D INVALID_PHYS_ADDR) { > > > > > > > - page =3D alloc_page(GFP_ATOMIC | __GF= P_NOFAIL); > > > > > > > memcpy_from_page(page_address(page), > > > > > > > map->bounce_page, 0,= PAGE_SIZE); > > > > > > > } > > > > > > > @@ -310,6 +327,7 @@ void vduse_domain_remove_user_bounce_page= s(struct vduse_iova_domain *domain) > > > > > > > map->bounce_page =3D page; > > > > > > > } > > > > > > > domain->user_bounce_pages =3D false; > > > > > > > + kfree(pages); > > > > > > > out: > > > > > > > write_unlock(&domain->bounce_lock); > > > > > > > } > > > > > > > @@ -543,10 +561,13 @@ static int vduse_domain_mmap(struct fil= e *file, struct vm_area_struct *vma) > > > > > > > static int vduse_domain_release(struct inode *inode, struct = file *file) > > > > > > > { > > > > > > > struct vduse_iova_domain *domain =3D file->private_da= ta; > > > > > > > + struct page **pages; > > > > > > > + > > > > > > > + pages =3D vduse_domain_alloc_pages_to_remove_bounce(d= omain); > > > > > > > > > > > > > > spin_lock(&domain->iotlb_lock); > > > > > > > vduse_iotlb_del_range(domain, 0, ULLONG_MAX); > > > > > > > - vduse_domain_remove_user_bounce_pages(domain); > > > > > > > + vduse_domain_remove_user_bounce_pages(domain, pages); > > > > > > > vduse_domain_free_kernel_bounce_pages(domain); > > > > > > > spin_unlock(&domain->iotlb_lock); > > > > > > > put_iova_domain(&domain->stream_iovad); > > > > > > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.h b/drivers/v= dpa/vdpa_user/iova_domain.h > > > > > > > index f92f22a7267d..17efa5555b3f 100644 > > > > > > > --- a/drivers/vdpa/vdpa_user/iova_domain.h > > > > > > > +++ b/drivers/vdpa/vdpa_user/iova_domain.h > > > > > > > @@ -74,7 +74,10 @@ void vduse_domain_reset_bounce_map(struct = vduse_iova_domain *domain); > > > > > > > int vduse_domain_add_user_bounce_pages(struct vduse_iova_dom= ain *domain, > > > > > > > struct page **pages, i= nt count); > > > > > > > > > > > > > > -void vduse_domain_remove_user_bounce_pages(struct vduse_iova= _domain *domain); > > > > > > > +void vduse_domain_remove_user_bounce_pages(struct vduse_iova= _domain *domain, > > > > > > > + struct page **page= s); > > > > > > > + > > > > > > > +struct page **vduse_domain_alloc_pages_to_remove_bounce(stru= ct vduse_iova_domain *domain); > > > > > > > > > > > > > > void vduse_domain_destroy(struct vduse_iova_domain *domain); > > > > > > > > > > > > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdp= a/vdpa_user/vduse_dev.c > > > > > > > index 7ae99691efdf..5d8d5810df57 100644 > > > > > > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c > > > > > > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c > > > > > > > @@ -1030,6 +1030,7 @@ static int vduse_dev_queue_irq_work(str= uct vduse_dev *dev, > > > > > > > static int vduse_dev_dereg_umem(struct vduse_dev *dev, > > > > > > > u64 iova, u64 size) > > > > > > > { > > > > > > > + struct page **pages; > > > > > > > int ret; > > > > > > > > > > > > > > mutex_lock(&dev->mem_lock); > > > > > > > @@ -1044,7 +1045,8 @@ static int vduse_dev_dereg_umem(struct = vduse_dev *dev, > > > > > > > if (dev->umem->iova !=3D iova || size !=3D dev->domai= n->bounce_size) > > > > > > > goto unlock; > > > > > > > > > > > > > > - vduse_domain_remove_user_bounce_pages(dev->domain); > > > > > > > + pages =3D vduse_domain_alloc_pages_to_remove_bounce(d= ev->domain); > > > > > > > + vduse_domain_remove_user_bounce_pages(dev->domain, pa= ges); > > > > > > > unpin_user_pages_dirty_lock(dev->umem->pages, > > > > > > > dev->umem->npages, true); > > > > > > > atomic64_sub(dev->umem->npages, &dev->umem->mm->pinne= d_vm); > > > > > > > > > > > > We miss a kfree(pages); here? > > > > > no. > > > > > i've moved it into vduse_domain_remove_user_bounce_pages. > > > > > > > > Ok, but it seems tricky e.g allocated by the caller but freed in > > > > callee. And I think I missed some important issues in the previous > > > > review: The check of user_bounce_pages must be done under the > > > > bounce_lock, otherwise it might race with umem_reg. > > > > > > > > So in the case of release(), we know the device is gone, so there's= no > > > > need to allocate pages that will be released soon. So we can pass N= ULL > > > > as a hint and just assign bounce_page to NULL in > > > > vduse_domain_remove_user_bounce_pages(). > > > > > > > > And in the case of vduse_dev_dereg_umem(), we need to allocate the > > > > pages without checking user_bounce_pages. So in > > > > vduse_domain_remove_user_bounce_pages() if we can free the allocate= d > > > > pages as well as the pages in the following check > > > > > > > > if (!domain->user_bounce_pages) > > > > goto out; > > > > > > > > What do you think? > > > > > > I am not a vdpa guy, but changing the current logic is another patch= . > > > From mm perspective, I can only address the __GFP_NOFAIL issue. > > > > > > I actually prefer you guys handle it directly:-) I'd rather report a= BUG > > > instead. TBH, I know nothing about vpda. > > > > Fine, let me post a patch for this (no later than the end of this week)= . > > > Jason, > Thank you very much. Also, Tetsuo reminded me that kmalloc_array() might = be > problematic if the count is too large: > pages =3D kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL= ); > I think it's a side effect of __GFP_NOFAIL? > You might want to consider using vmalloc_array() or kvmalloc_array() inst= ead > when you send a new version. Will consider that. Thanks > > > Thanks > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > -- > > > > > > > 2.34.1 > > > > > > > > > > > > > > > Thanks > Barry >