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[34.86.254.150]) by smtp.gmail.com with ESMTPSA id d27-20020a05620a137b00b00788228fbe05sm2851589qkl.17.2024.03.11.09.46.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Mar 2024 09:46:47 -0700 (PDT) From: Pasha Tatashin To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, x86@kernel.org, bp@alien8.de, brauner@kernel.org, bristot@redhat.com, bsegall@google.com, dave.hansen@linux.intel.com, dianders@chromium.org, dietmar.eggemann@arm.com, eric.devolder@oracle.com, hca@linux.ibm.com, hch@infradead.org, hpa@zytor.com, jacob.jun.pan@linux.intel.com, jgg@ziepe.ca, jpoimboe@kernel.org, jroedel@suse.de, juri.lelli@redhat.com, kent.overstreet@linux.dev, kinseyho@google.com, kirill.shutemov@linux.intel.com, lstoakes@gmail.com, luto@kernel.org, mgorman@suse.de, mic@digikod.net, michael.christie@oracle.com, mingo@redhat.com, mjguzik@gmail.com, mst@redhat.com, npiggin@gmail.com, peterz@infradead.org, pmladek@suse.com, rick.p.edgecombe@intel.com, rostedt@goodmis.org, surenb@google.com, tglx@linutronix.de, urezki@gmail.com, vincent.guittot@linaro.org, vschneid@redhat.com, pasha.tatashin@soleen.com Subject: [RFC 04/14] fork: Remove assumption that vm_area->nr_pages equals to THREAD_SIZE Date: Mon, 11 Mar 2024 16:46:28 +0000 Message-ID: <20240311164638.2015063-5-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.44.0.278.ge034bb2e1d-goog In-Reply-To: <20240311164638.2015063-1-pasha.tatashin@soleen.com> References: <20240311164638.2015063-1-pasha.tatashin@soleen.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In many places number of pages in the stack is detremined via (THREAD_SIZE / PAGE_SIZE). There is also a BUG_ON() that ensures that (THREAD_SIZE / PAGE_SIZE) is indeed equals to vm_area->nr_pages. However, with dynamic stacks, the number of pages in vm_area will grow with stack, therefore, use vm_area->nr_pages to determine the actual number of pages allocated in stack. Signed-off-by: Pasha Tatashin --- kernel/fork.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index 60e812825a7a..a35f4008afa0 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -243,13 +243,11 @@ static int free_vm_stack_cache(unsigned int cpu) =20 static int memcg_charge_kernel_stack(struct vm_struct *vm) { - int i; - int ret; + int i, ret, nr_pages; int nr_charged =3D 0; =20 - BUG_ON(vm->nr_pages !=3D THREAD_SIZE / PAGE_SIZE); - - for (i =3D 0; i < THREAD_SIZE / PAGE_SIZE; i++) { + nr_pages =3D vm->nr_pages; + for (i =3D 0; i < nr_pages; i++) { ret =3D memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0); if (ret) goto err; @@ -531,9 +529,10 @@ static void account_kernel_stack(struct task_struct *t= sk, int account) { if (IS_ENABLED(CONFIG_VMAP_STACK)) { struct vm_struct *vm =3D task_stack_vm_area(tsk); - int i; + int i, nr_pages; =20 - for (i =3D 0; i < THREAD_SIZE / PAGE_SIZE; i++) + nr_pages =3D vm->nr_pages; + for (i =3D 0; i < nr_pages; i++) mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB, account * (PAGE_SIZE / 1024)); } else { @@ -551,10 +550,11 @@ void exit_task_stack_account(struct task_struct *tsk) =20 if (IS_ENABLED(CONFIG_VMAP_STACK)) { struct vm_struct *vm; - int i; + int i, nr_pages; =20 vm =3D task_stack_vm_area(tsk); - for (i =3D 0; i < THREAD_SIZE / PAGE_SIZE; i++) + nr_pages =3D vm->nr_pages; + for (i =3D 0; i < nr_pages; i++) memcg_kmem_uncharge_page(vm->pages[i], 0); } } --=20 2.44.0.278.ge034bb2e1d-goog