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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, Mateusz Guzik , Pasha Tatashin Subject: Re: [PATCH] fork: zero vmap stack using clear_pages() instead of memset() Message-ID: <12c53268-b5a4-4725-b376-b7795bc4057c@lucifer.local> References: <20260224-mm-fork-clear-pages-v1-1-184c65a72d49@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260224-mm-fork-clear-pages-v1-1-184c65a72d49@kernel.org> X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 276FD1A0012 X-Stat-Signature: 3awqpd5yjatttw1fjemhtf53n6d9ixxg X-HE-Tag: 1772798422-529184 X-HE-Meta: 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 WHPzb0QC T9X35nPupeWBTxFEqXSf/tK5g4S1ZB3GXY+FvFcDi1KNKQefQdyv3OTlCwkNZs7KW9CgfPZ6YSwLoOaCHbC6RCqWcUGFpttNW1E+7QepllvIoL57pBXTr4lwsopoDWkI3allUnn9zd2o4ZDTF05EWOXeMaiU1+YyZ2WqKUnguk8ybJ3NrdaYiZg2CpVpRXD+XBUPvte67brWO++EG9ZCR9pqQWcr8m9TNtvIhl/oBvYXkYVf8QAGJF2KsVNPjx9YjVPBJ61EgyBD+tDWc/S1S08faPeOZHjxZwUH55U2CEJ0xxN163pbiFm9DT5ZRVDgLKv6I/SgwvS0xnCGEYBUfDvd5eqng6zXeiDSwHP6y2W+b7VJ0BowgGbppfG12zLG3J1QRhAwgYYosvQGpgCPAUw+Azg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Feb 24, 2026 at 11:26:32AM +0100, Linus Walleij wrote: > After the introduction of clear_pages() we exploit the > fact that the process vm_area is allocated in contiguous > pages to just clear them all in one swift operation. > > Suggested-by: Mateusz Guzik > Link: https://lore.kernel.org/linux-mm/dpnwsp7dl4535rd7qmszanw6u5an2p74uxfex4dh53frpb7pu3@2bnjjavjrepe/ > Suggested-by: Pasha Tatashin > Link: https://lore.kernel.org/20240311164638.2015063-7-pasha.tatashin@soleen.com > Signed-off-by: Linus Walleij LGTM, so: Reviewed-by: Lorenzo Stoakes (Oracle) > --- > kernel/fork.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/fork.c b/kernel/fork.c > index e832da9d15a4..88d78ccef245 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -345,7 +345,7 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node) > stack = kasan_reset_tag(vm_area->addr); > > /* Clear stale pointers from reused stack. */ > - memset(stack, 0, THREAD_SIZE); > + clear_pages(vm_area->addr, vm_area->nr_pages); > > tsk->stack_vm_area = vm_area; > tsk->stack = stack; > > --- > base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f > change-id: 20260224-mm-fork-clear-pages-ae7c52d12a93 > > Best regards, > -- > Linus Walleij > >