From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AF86D1D545 for ; Mon, 22 Apr 2024 21:28:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713821316; cv=none; b=mrF+1qqBO6hXdKQVKnJbsk1sA18Xy3uUxvr69SyxWmHXcETwp3+mwbwgy3iFDIzyyIaTmzV/AY+UGDNBxAft2HFs4r/j0QdgDL/IOS2CpqWeaLjY3ozJX21MvBjvIskNcbE8HUtOBqXaxigQ5n7zVJGgON6mVWxKLQDeG0eSy1c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713821316; c=relaxed/simple; bh=itR0dMitJ2NlCR82j3JWy6OQZ6XqxLec96clwAPS/5A=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=TtO0obEAcdiOZLChi6+mPUrRRm109KC+SqByoGUNm6y8xHlliWlRnNfJbSwKz2rXRoRUZmEI4Eqjt5X0wg7W7OFkS+jrSnIFA1HwbjmDc4SeSFdfkXiZLYBhVndYUq24qJrhCodr3acfUwV1CASqFMFeTWhB2o7xh2OcHemmUe4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=OkoG1IKE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="OkoG1IKE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E7A2CC113CC; Mon, 22 Apr 2024 21:28:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1713821316; bh=itR0dMitJ2NlCR82j3JWy6OQZ6XqxLec96clwAPS/5A=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=OkoG1IKEfI+0ioKSLycirL/K1vFKFCP9Mg+mXh/2NPhjfxSYxkscRC224VhUrpqlm ut39oY5YVyCTDXOETHlGj/s8vDmquE7/5fhe6KgMqKV6ZvSo5iypocWzgCLhrgLOtq kzv/6mCiBEGDyRknt1D+c2vGg2bza38eJ44Jqt1I= Date: Mon, 22 Apr 2024 14:28:35 -0700 From: Andrew Morton To: Hariom Panthi Cc: urezki@gmail.com, hch@infradead.org, lstoakes@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, maninder1.s@samsung.com, r.thapliyal@samsung.com Subject: Re: [PATCH 1/1] mm: vmalloc: dump page owner info if page is already mapped Message-Id: <20240422142835.3a2fe7740dfc3003b68de305@linux-foundation.org> In-Reply-To: <20240419043910.2156379-1-hariom1.p@samsung.com> References: <20240419043910.2156379-1-hariom1.p@samsung.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 19 Apr 2024 10:09:10 +0530 Hariom Panthi wrote: > In vmap_pte_range, BUG_ON is called when page is already mapped, > It doesn't give enough information to debug further. > Dumping page owner information alongwith BUG_ON will be more useful > in case of multiple page mapping. > > Example: > [ 18.258806] page_owner tracks the page as allocated > [ 18.258970] page last allocated via order 0, migratetype Unmovable, gfp_mask 0xcc0(GFP_KERNEL), pid 81, tgid 81 (insmod), ts 18257811008, free_ts 0 > [ 18.259327] prep_new_page+0xa8/0x10c > [ 18.259455] get_page_from_freelist+0x7f8/0x1248 > [ 18.259591] __alloc_pages+0x164/0x2b4 > [ 18.259703] alloc_pages_mpol+0x88/0x230 > [ 18.259821] alloc_pages+0x4c/0x7c > [ 18.259923] load_module+0x74/0x1af4 > [ 18.260031] __do_sys_init_module+0x190/0x1fc > [ 18.260154] __arm64_sys_init_module+0x1c/0x28 > [ 18.260280] invoke_syscall+0x44/0x108 > [ 18.260394] el0_svc_common.constprop.0+0x40/0xe0 > [ 18.260530] do_el0_svc_compat+0x1c/0x34 > [ 18.260647] el0_svc_compat+0x2c/0x80 > [ 18.260761] el0t_32_sync_handler+0x90/0x140 > [ 18.260887] el0t_32_sync+0x194/0x198 > [ 18.260996] page_owner free stack trace missing > [ 18.261143] ------------[ cut here ]------------ > [ 18.261272] kernel BUG at mm/vmalloc.c:113! > > ... > > @@ -103,7 +105,13 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, > if (!pte) > return -ENOMEM; > do { > - BUG_ON(!pte_none(ptep_get(pte))); > + if (!pte_none(ptep_get(pte))) { > + if (pfn_valid(pfn)) { > + page = pfn_to_page(pfn); > + dump_page_owner(page); > + } > + BUG(); > + } Diving straight into dump_page_owner() seems inappropriate. The higher-level dump_page() interface is more typically used. Or, even more common, VM_BUG_ON_PAGE(), but that doesn't look to be a good fit here.