I turned on UBSAN on most of my test machines and found this recurring pattern: shift exponent -1 from ext4_mb_init_cache(). This happens in both 4.5 and 4.6-rc2. gcc version 5.3.1 20160409 (Debian 5.3.1-14) [ 43.297258] ================================================================================ [ 43.297442] UBSAN: Undefined behaviour in fs/ext4/mballoc.c:1281:11 [ 43.297542] shift exponent -1 is negative [ 43.297637] CPU: 1 PID: 1001 Comm: mv Not tainted 4.6.0-rc2 #20 [ 43.297731] Hardware name: Unknown Unknown/S2462 THUNDER K7, BIOS Guinness-8 04/07/2003 [ 43.297891] 00000000 c134bb3c 00000046 f45eb944 00000001 c1381c4b f45eb938 ffffffff [ 43.298251] c13821d6 c16ff14c f45eb948 00000005 f6055770 00000202 f600312d f442f000 [ 43.298604] 00000000 00008000 00001800 f6627800 0000001f f4695000 00008000 00001789 [ 43.298960] Call Trace: [ 43.299065] [<c134bb3c>] ? dump_stack+0x45/0x69 [ 43.299162] [<c1381c4b>] ? ubsan_epilogue+0xb/0x40 [ 43.299258] [<c13821d6>] ? __ubsan_handle_shift_out_of_bounds+0xd6/0x120 [ 43.299361] [<c12953eb>] ? ext4_mb_init_cache+0x4cb/0xc20 [ 43.299457] [<c1290509>] ? mb_find_order_for_block+0xd9/0x110 [ 43.299552] [<c1290cef>] ? mb_find_extent+0x9f/0x3d0 [ 43.299648] [<c1293d98>] ? ext4_mb_complex_scan_group+0xf8/0x4c0 [ 43.299751] [<c113ca8f>] ? pagecache_get_page+0x1cf/0x3c0 [ 43.299847] [<c129a5d2>] ? ext4_mb_regular_allocator+0x292/0x620 [ 43.299945] [<c129000c>] ? ext4_mb_free_metadata+0x41c/0x840 [ 43.300043] [<c129d7e6>] ? ext4_mb_new_blocks+0x376/0x8a0 [ 43.300141] [<c128108f>] ? ext4_find_extent+0x2ff/0x480 [ 43.300240] [<c1463c4b>] ? scsi_dispatch_cmd+0xfb/0x250 [ 43.300335] [<c12873e3>] ? ext4_ext_map_blocks+0xa43/0x1430 [ 43.300436] [<c131f66c>] ? blk_rq_map_sg+0x21c/0x800 [ 43.300532] [<c132a11f>] ? __bt_get+0x12f/0x400 [ 43.300630] [<c1490001>] ? ata_scsi_cmd_error_handler+0x191/0x270 [ 43.300732] [<c1250f59>] ? ext4_map_blocks+0x139/0x5a0 [ 43.300827] [<c148ae6b>] ? ata_scsi_translate+0xbb/0x1f0 [ 43.300922] [<c148a410>] ? ata_scsi_invalid_field+0x50/0x50 [ 43.301019] [<c1256013>] ? mpage_map_and_submit_extent+0xe3/0xce0 [ 43.301121] [<c1152254>] ? release_pages+0xe4/0x430 [ 43.301169] [<c1153b56>] ? __pagevec_release+0x26/0x40 [ 43.301169] [<c12ba968>] ? jbd2__journal_start+0xc8/0x1f0 [ 43.301169] [<c128c17d>] ? __ext4_journal_start_sb+0x4d/0xd0 [ 43.301169] [<c125700f>] ? ext4_writepages+0x3ff/0x7d0 [ 43.301169] [<c12642a0>] ? ext4_find_entry+0x730/0xb60 [ 43.301169] [<c1150289>] ? do_writepages+0x29/0x80 [ 43.301169] [<c113ddc5>] ? __filemap_fdatawrite_range+0x75/0xc0 [ 43.301169] [<c113ded3>] ? filemap_flush+0x23/0x30 [ 43.301169] [<c1268a21>] ? ext4_rename2+0x971/0x1680 [ 43.301169] [<c11ba2a8>] ? unlazy_walk+0x88/0x2a0 [ 43.301169] [<c11b9e2e>] ? terminate_walk+0x6e/0x190 [ 43.301169] [<c12680b0>] ? ext4_tmpfile+0x190/0x190 [ 43.301169] [<c11c10e0>] ? vfs_rename+0x6e0/0xaf0 [ 43.301169] [<c12680b0>] ? ext4_tmpfile+0x190/0x190 [ 43.301169] [<c11c44d3>] ? SyS_rename+0x353/0x3f0 [ 43.301169] [<c1002076>] ? do_fast_syscall_32+0xb6/0x1d0 [ 43.301169] [<c164cedb>] ? sysenter_past_esp+0x40/0x6a [ 43.301169] ================================================================================ -- Meelis Roos (mroos@xxxxxxxx) -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
