Messages in this thread | | | From | Bernard Metzler <> | Subject | RE: Re: [RFC PATCH 05/19] RMDA/siw: Convert to use vm_account | Date | Mon, 30 Jan 2023 13:27:53 +0000 |
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> -----Original Message----- > From: Alistair Popple <apopple@nvidia.com> > Sent: Monday, 30 January 2023 12:35 > To: Bernard Metzler <BMT@zurich.ibm.com> > Cc: Jason Gunthorpe <jgg@nvidia.com>; linux-mm@kvack.org; > cgroups@vger.kernel.org; linux-kernel@vger.kernel.org; jhubbard@nvidia.com; > tjmercier@google.com; hannes@cmpxchg.org; surenb@google.com; > mkoutny@suse.com; daniel@ffwll.ch; Leon Romanovsky <leon@kernel.org>; > linux-rdma@vger.kernel.org > Subject: [EXTERNAL] Re: [RFC PATCH 05/19] RMDA/siw: Convert to use > vm_account > > > Bernard Metzler <BMT@zurich.ibm.com> writes: > > >> -----Original Message----- > >> From: Jason Gunthorpe <jgg@nvidia.com> > >> Sent: Tuesday, 24 January 2023 15:37 > >> To: Alistair Popple <apopple@nvidia.com> > >> Cc: linux-mm@kvack.org; cgroups@vger.kernel.org; linux- > >> kernel@vger.kernel.org; jhubbard@nvidia.com; tjmercier@google.com; > >> hannes@cmpxchg.org; surenb@google.com; mkoutny@suse.com; > daniel@ffwll.ch; > >> Bernard Metzler <BMT@zurich.ibm.com>; Leon Romanovsky <leon@kernel.org>; > >> linux-rdma@vger.kernel.org > >> Subject: [EXTERNAL] Re: [RFC PATCH 05/19] RMDA/siw: Convert to use > >> vm_account > >> > >> On Tue, Jan 24, 2023 at 04:42:34PM +1100, Alistair Popple wrote: > >> > >> > @@ -385,20 +382,16 @@ struct siw_umem *siw_umem_get(u64 start, u64 > len, > >> bool writable) > >> > if (!umem) > >> > return ERR_PTR(-ENOMEM); > >> > > >> > - mm_s = current->mm; > >> > - umem->owning_mm = mm_s; > >> > umem->writable = writable; > >> > > >> > - mmgrab(mm_s); > >> > + vm_account_init_current(&umem->vm_account); > >> > > >> > if (writable) > >> > foll_flags |= FOLL_WRITE; > >> > > >> > - mmap_read_lock(mm_s); > >> > + mmap_read_lock(current->mm); > >> > > >> > - mlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; > >> > - > >> > - if (num_pages + atomic64_read(&mm_s->pinned_vm) > mlock_limit) { > >> > + if (vm_account_pinned(&umem->vm_account, num_pages)) { > >> > rv = -ENOMEM; > >> > goto out_sem_up; > >> > } > >> > @@ -429,7 +422,6 @@ struct siw_umem *siw_umem_get(u64 start, u64 len, > >> bool writable) > >> > goto out_sem_up; > >> > > >> > umem->num_pages += rv; > >> > - atomic64_add(rv, &mm_s->pinned_vm); > >> > >> Also fixes the race bug > > > > But introduces another one. In that loop, umem->num_pages keeps the > > number of pages currently pinned, not the target number. The current > > patch uses that umem->num_pages to call vm_unaccount_pinned() in > > siw_umem_release(). Bailing out before all pages are pinned would > > mess up that accounting during release. Maybe introduce another > > parameter to siw_umem_release(), or better have another umem member > > 'umem->num_pages_accounted' for correct accounting during release. > > Yes, I see the problem thanks for pointing it out. Will fix for the next > version.
Thank you! Let me send a patch to the original code, just checking if not all pages are pinned and fix the counter accordingly. Maybe you can go from there..?
Thank you, Bernard.
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