On 01/23/2018 09:36 PM, Michal Hocko wrote: > On Tue 23-01-18 21:28:28, Anshuman Khandual wrote: >> On 01/23/2018 06:15 PM, Michal Hocko wrote: >>> On Tue 23-01-18 16:55:18, Anshuman Khandual wrote: >>>> On 01/17/2018 01:37 PM, Michal Hocko wrote: >>>>> On Thu 11-01-18 15:38:37, Anshuman Khandual wrote: >>>>>> On 01/09/2018 09:43 PM, Michal Hocko wrote: >>>>> [...] >>>>>>> Did you manage to catch _who_ is requesting that anonymous mapping? Do >>>>>>> you need a help with the debugging patch? >>>>>> >>>>>> Not yet, will get back on this. >>>>> >>>>> ping? >>>> >>>> Hey Michal, >>>> >>>> Missed this thread, my apologies. This problem is happening only with >>>> certain binaries like 'sed', 'tmux', 'hostname', 'pkg-config' etc. As >>>> you had mentioned before the map request collision is happening on >>>> [10030000, 10040000] and [10030000, 10040000] ranges only which is >>>> just a single PAGE_SIZE. You asked previously that who might have >>>> requested the anon mapping which is already present in there ? Would >>>> not that be the same process itself ? I am bit confused. >>> >>> We are early in the ELF loading. If we are mapping over an existing >>> mapping then we are effectivelly corrupting it. In other words exactly >>> what this patch tries to prevent. I fail to see what would be a relevant >>> anon mapping this early and why it would be colliding with elf >>> segements. >>> >>>> Would it be >>>> helpful to trap all the mmap() requests from any of the binaries >>>> and see where we might have created that anon mapping ? >>> >>> Yeah, that is exactly what I was suggesting. Sorry for not being clear >>> about that. >>> >> >> Tried to instrument just for the 'sed' binary and dont see any where >> it actually requests the anon VMA which got hit when loading the ELF >> section which is strange. All these requested flags here already has >> MAP_FIXED_NOREPLACE (0x100000). Wondering from where the anon VMA >> actually came from. > > Could you try to dump backtrace? This is when it fails inside elf_map() function due to collision with existing anon VMA mapping. [c000201c9ad07880] [c000000000b0b4c0] dump_stack+0xb0/0xf0 (unreliable) [c000201c9ad078c0] [c0000000003c4550] elf_map+0x2d0/0x310 [c000201c9ad07b60] [c0000000003c6258] load_elf_binary+0x6f8/0x158c [c000201c9ad07c80] [c000000000352900] search_binary_handler+0xd0/0x270 [c000201c9ad07d10] [c000000000354838] do_execveat_common.isra.31+0x658/0x890 [c000201c9ad07df0] [c000000000354e80] SyS_execve+0x40/0x50 [c000201c9ad07e30] [c00000000000b220] system_call+0x58/0x6c -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
