Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758582AbXLOBJ5 (ORCPT ); Fri, 14 Dec 2007 20:09:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753625AbXLOBJq (ORCPT ); Fri, 14 Dec 2007 20:09:46 -0500 Received: from gir.skynet.ie ([193.1.99.77]:48192 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753568AbXLOBJp (ORCPT ); Fri, 14 Dec 2007 20:09:45 -0500 Date: Sat, 15 Dec 2007 01:09:41 +0000 From: Mel Gorman To: Andrew Morton Cc: James Bottomley , jens.axboe@oracle.com, liml@rtr.ca, lkml@rtr.ca, matthew@wil.cx, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, linux-mm@kvack.org Subject: Re: QUEUE_FLAG_CLUSTER: not working in 2.6.24 ? Message-ID: <20071215010940.GB28613@csn.ul.ie> References: <476188C4.9030802@rtr.ca> <20071213193937.GG10104@kernel.dk> <47618B0B.8020203@rtr.ca> <20071213195350.GH10104@kernel.dk> <20071213200219.GI10104@kernel.dk> <476190BE.9010405@rtr.ca> <20071213200958.GK10104@kernel.dk> <20071213140207.111f94e2.akpm@linux-foundation.org> <1197584106.3154.55.camel@localhost.localdomain> <20071213142935.47ff19d9.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20071213142935.47ff19d9.akpm@linux-foundation.org> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6064 Lines: 153 On (13/12/07 14:29), Andrew Morton didst pronounce: > > The simple way seems to be to malloc a large area, touch every page and > > then look at the physical pages assigned ... they now mostly seem to be > > descending in physical address. > > > > OIC. -mm's /proc/pid/pagemap can be used to get the pfn's... > I tried using pagemap to verify the patch but it triggered BUG_ON checks. Perhaps I am using the interface wrong but I would still not expect it to break in this fashion. I tried 2.6.24-rc4-mm1, 2.6.24-rc5-mm1, 2.6.24-rc5 with just the maps4 patches applied and 2.6.23 with maps4 patches applied. Each time I get errors like this; [ 90.108315] BUG: sleeping function called from invalid context at include/asm/uaccess_32.h:457 [ 90.211227] in_atomic():1, irqs_disabled():0 [ 90.262251] no locks held by showcontiguous/2814. [ 90.318475] Pid: 2814, comm: showcontiguous Not tainted 2.6.24-rc5 #1 [ 90.395344] [] show_trace_log_lvl+0x1a/0x30 [ 90.456948] [] show_trace+0x12/0x20 [ 90.510173] [] dump_stack+0x6e/0x80 [ 90.563409] [] __might_sleep+0xc3/0xe0 [ 90.619765] [] copy_to_user+0x3d/0x60 [ 90.675153] [] add_to_pagemap+0x5c/0x80 [ 90.732513] [] pagemap_pte_range+0x68/0xb0 [ 90.793010] [] walk_page_range+0x112/0x210 [ 90.853482] [] pagemap_read+0x176/0x220 [ 90.910863] [] vfs_read+0x94/0x150 [ 90.963058] [] sys_read+0x3d/0x70 [ 91.014219] [] syscall_call+0x7/0xb [ 91.067433] ======================= [ 91.110137] BUG: scheduling while atomic: showcontiguous/2814/0x00000001 [ 91.190169] no locks held by showcontiguous/2814. [ 91.246293] Pid: 2814, comm: showcontiguous Not tainted 2.6.24-rc5 #1 [ 91.323145] [] show_trace_log_lvl+0x1a/0x30 [ 91.384633] [] show_trace+0x12/0x20 [ 91.437878] [] dump_stack+0x6e/0x80 [ 91.491116] [] __schedule_bug+0x66/0x70 [ 91.548467] [] schedule+0x556/0x7b0 [ 91.601698] [] work_resched+0x5/0x21 [ 91.655977] ======================= [ 91.704927] showcontiguous[2814]: segfault at b7eaa900 eip b7eaa900 esp bfa02e8c error 4 [ 91.801633] BUG: scheduling while atomic: showcontiguous/2814/0x00000001 [ 91.881634] no locks held by showcontiguous/2814. [ 91.937779] Pid: 2814, comm: showcontiguous Not tainted 2.6.24-rc5 #1 [ 92.014606] [] show_trace_log_lvl+0x1a/0x30 [ 92.076123] [] show_trace+0x12/0x20 [ 92.129354] [] dump_stack+0x6e/0x80 [ 92.182567] [] __schedule_bug+0x66/0x70 [ 92.239959] [] schedule+0x556/0x7b0 [ 92.293187] [] work_resched+0x5/0x21 [ 92.347452] ======================= [ 92.392697] note: showcontiguous[2814] exited with preempt_count 1 [ 92.468611] BUG: scheduling while atomic: showcontiguous/2814/0x10000001 [ 92.548588] no locks held by showcontiguous/2814. [ 92.604732] Pid: 2814, comm: showcontiguous Not tainted 2.6.24-rc5 #1 [ 92.681665] [] show_trace_log_lvl+0x1a/0x30 [ 92.743180] [] show_trace+0x12/0x20 [ 92.796409] [] dump_stack+0x6e/0x80 [ 92.849621] [] __schedule_bug+0x66/0x70 [ 92.907014] [] schedule+0x556/0x7b0 [ 92.960349] [] __cond_resched+0x27/0x40 [ 93.017804] [] cond_resched+0x2a/0x40 [ 93.073122] [] unmap_vmas+0x4ec/0x540 [ 93.128418] [] exit_mmap+0x6f/0xf0 [ 93.180611] [] mmput+0x31/0xb0 [ 93.228665] [] exit_mm+0x8d/0xf0 [ 93.278788] [] do_exit+0x15f/0x7e0 [ 93.330965] [] do_group_exit+0x29/0x70 [ 93.387321] [] get_signal_to_deliver+0x2b7/0x490 [ 93.454013] [] do_notify_resume+0x7d/0x760 [ 93.514476] [] work_notifysig+0x13/0x1a [ 93.571869] ======================= Just using cp to read the file is enough to cause problems but I included a very basic program below that produces the BUG_ON checks. Is this a known issue or am I using the interface incorrectly? #include #include #include #include #include #include #include #include #define MAPSIZE (4*1048576) #define PM_ENTRY_BYTES sizeof(__u64) int main(int argc, char **argv) { int pagemap_fd; unsigned long *anonmapping; __u64 pagemap_entry = 0ULL; unsigned long vpfn, ppfn; size_t mmap_offset; int pagesize = getpagesize(); /* Open the pagemap interface */ pagemap_fd = open("/proc/self/pagemap", O_RDONLY); if (pagemap_fd == -1) { perror("fopen"); exit(EXIT_FAILURE); } /* Create an anonymous mapping */ anonmapping = mmap(NULL, MAPSIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_POPULATE, -1, 0); if (anonmapping == MAP_FAILED) { perror("mmap"); exit(1); } /* Work out the VPN the mapping is at and seek to it in pagemap */ vpfn = ((unsigned long)anonmapping) / pagesize; mmap_offset = lseek(pagemap_fd, vpfn * PM_ENTRY_BYTES, SEEK_SET); if (mmap_offset == -1) { perror("fseek"); exit(EXIT_FAILURE); } /* Read the PFN of each page in the mapping */ for (mmap_offset = 0; mmap_offset < MAPSIZE; mmap_offset += pagesize) { vpfn = ((unsigned long)anonmapping + mmap_offset) / pagesize; if (read(pagemap_fd, &pagemap_entry, PM_ENTRY_BYTES) == 0) { perror("fread"); exit(EXIT_FAILURE); } ppfn = (unsigned long)pagemap_entry; printf("vpfn = %8lu ppfn = %8lu\n", vpfn, ppfn); } close(pagemap_fd); munmap(anonmapping, MAPSIZE); exit(EXIT_SUCCESS); } -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/