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[209.85.220.65]) by mx.google.com with SMTPS id f1sor6883117ljf.40.2019.02.26.04.13.18 for (Google Transport Security); Tue, 26 Feb 2019 04:13:18 -0800 (PST) Received-SPF: pass (google.com: domain of jrdr.linux@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b="BTT/af11"; spf=pass (google.com: domain of jrdr.linux@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=jrdr.linux@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=DT0qlgg8yLGWJfZNXVHCGnHtRXa+0hWQ5l9kpD9jVV8=; b=BTT/af11Af4g7Z8+iUJtkrhRpsF18FwF+w/DZHgvAt3DMkp0DR3DZI5Xl4r06i9MiA yRnQaNrTgCz3u/9qEbJRf4Rx2S0rDLKR7sB4loDcv4vOOHEpJPBdduj3TNHoA0HlD76/ 8eau9Nwao+bFFEgDH+m0fkUaSdIi9Jzr2zz9WxUIxY9mSAUuojWBfkWXMh6cFJR7ctX4 U0p3y02ujuSIqgyV6QthnsOFiMMQgzVEo4P7qNOSs0twzddPrSmfTbudjODRwAuIVbwl 3Enu7havs7HWL3lMXY03THVCMsyGFlrnMdQ0FxTPU7HiSlWmly/P1p5byZd3t9Q6CpgZ T2wQ== X-Google-Smtp-Source: AHgI3IbqBHCDYCt00RIdjo12W+Ik6ICDGxRWE+n+JCPu9cfQgZ/db+khrZWu0PfllbqgyVIo+DTu4bpAmvZ+uT1UBs4= X-Received: by 2002:a2e:240a:: with SMTP id k10mr13038482ljk.31.1551183198318; Tue, 26 Feb 2019 04:13:18 -0800 (PST) MIME-Version: 1.0 References: <20190225191710.48131-1-cai@lca.pw> In-Reply-To: <20190225191710.48131-1-cai@lca.pw> From: Souptick Joarder Date: Tue, 26 Feb 2019 17:43:06 +0530 Message-ID: Subject: Re: [PATCH] mm/hotplug: fix an imbalance with DEBUG_PAGEALLOC To: Qian Cai Cc: Andrew Morton , Linux-MM , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" 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: On Tue, Feb 26, 2019 at 12:47 AM Qian Cai wrote: > > When onlining memory pages, it calls kernel_unmap_linear_page(), > However, it does not call kernel_map_linear_page() while offlining > memory pages. As the result, it triggers a panic below while onlining on > ppc64le as it checks if the pages are mapped before unmapping, > Therefore, let it call kernel_map_linear_page() when setting all pages > as reserved. > > kernel BUG at arch/powerpc/mm/hash_utils_64.c:1815! > Oops: Exception in kernel mode, sig: 5 [#1] > LE SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA pSeries > CPU: 2 PID: 4298 Comm: bash Not tainted 5.0.0-rc7+ #15 > NIP: c000000000062670 LR: c00000000006265c CTR: 0000000000000000 > REGS: c0000005bf8a75b0 TRAP: 0700 Not tainted (5.0.0-rc7+) > MSR: 800000000282b033 CR: 28422842 XER: 00000000 > CFAR: c000000000804f44 IRQMASK: 1 > GPR00: c00000000006265c c0000005bf8a7840 c000000001518200 c0000000013cbcc8 > GPR04: 0000000000080004 0000000000000000 00000000ccc457e0 c0000005c4e341d8 > GPR08: 0000000000000000 0000000000000001 c000000007f4f800 0000000000000001 > GPR12: 0000000000002200 c000000007f4e100 0000000000000000 0000000139c29710 > GPR16: 0000000139c29714 0000000139c29788 c0000000013cbcc8 0000000000000000 > GPR20: 0000000000034000 c0000000016e05e8 0000000000000000 0000000000000001 > GPR24: 0000000000bf50d9 800000000000018e 0000000000000000 c0000000016e04b8 > GPR28: f000000000d00040 0000006420a2f217 f000000000d00000 00ea1b2170340000 > NIP [c000000000062670] __kernel_map_pages+0x2e0/0x4f0 > LR [c00000000006265c] __kernel_map_pages+0x2cc/0x4f0 > Call Trace: > [c0000005bf8a7840] [c00000000006265c] __kernel_map_pages+0x2cc/0x4f0 (unreliable) > [c0000005bf8a78d0] [c00000000028c4a0] free_unref_page_prepare+0x2f0/0x4d0 > [c0000005bf8a7930] [c000000000293144] free_unref_page+0x44/0x90 > [c0000005bf8a7970] [c00000000037af24] __online_page_free+0x84/0x110 > [c0000005bf8a79a0] [c00000000037b6e0] online_pages_range+0xc0/0x150 > [c0000005bf8a7a00] [c00000000005aaa8] walk_system_ram_range+0xc8/0x120 > [c0000005bf8a7a50] [c00000000037e710] online_pages+0x280/0x5a0 > [c0000005bf8a7b40] [c0000000006419e4] memory_subsys_online+0x1b4/0x270 > [c0000005bf8a7bb0] [c000000000616720] device_online+0xc0/0xf0 > [c0000005bf8a7bf0] [c000000000642570] state_store+0xc0/0x180 > [c0000005bf8a7c30] [c000000000610b2c] dev_attr_store+0x3c/0x60 > [c0000005bf8a7c50] [c0000000004c0a50] sysfs_kf_write+0x70/0xb0 > [c0000005bf8a7c90] [c0000000004bf40c] kernfs_fop_write+0x10c/0x250 > [c0000005bf8a7ce0] [c0000000003e4b18] __vfs_write+0x48/0x240 > [c0000005bf8a7d80] [c0000000003e4f68] vfs_write+0xd8/0x210 > [c0000005bf8a7dd0] [c0000000003e52f0] ksys_write+0x70/0x120 > [c0000005bf8a7e20] [c00000000000b000] system_call+0x5c/0x70 > Instruction dump: > 7fbd5278 7fbd4a78 3e42ffeb 7bbd0640 3a523ac8 7e439378 487a2881 60000000 > e95505f0 7e6aa0ae 6a690080 7929c9c2 <0b090000> 7f4aa1ae 7e439378 487a28dd > > Signed-off-by: Qian Cai > --- > mm/page_alloc.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 10d0f2ed9f69..025fc93d1518 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -8349,6 +8349,7 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) > for (i = 0; i < (1 << order); i++) > SetPageReserved((page+i)); > pfn += (1 << order); > + kernel_map_pages(page, 1 << order, 1); Doubt , Not sure, but does this change will have any impact on drivers/base/memory.c#L249 memory_block_action() -> offline_pages() ? > } > spin_unlock_irqrestore(&zone->lock, flags); > } > -- > 2.17.2 (Apple Git-113) >