On 01/05/2018 02:16 PM, Michal Hocko wrote: > On Fri 05-01-18 12:13:17, Anshuman Khandual wrote: >> On 01/05/2018 05:50 AM, akpm@xxxxxxxxxxxxxxxxxxxx wrote: >>> The mm-of-the-moment snapshot 2018-01-04-16-19 has been uploaded to [...] >>> >>> This tree is partially included in linux-next. To see which patches are >>> included in linux-next, consult the `series' file. Only the patches >>> within the #NEXT_PATCHES_START/#NEXT_PATCHES_END markers are included in >>> linux-next. >>> >>> A git tree which contains the memory management portion of this tree is >>> maintained at git://git.kernel.org/pub/scm/linux/kernel/git/mhocko/mm.git >> Seems like this latest snapshot mmotm-2018-01-04-16-19 has not been >> updated in this git tree. I could not fetch not it shows up in the >> http link below. >> >> https://git.kernel.org/pub/scm/linux/kernel/git/mhocko/mm.git > I will update the tree today (WIP). This is not a fully automated > process and Andrew pushed his tree during my night ;) So be patient > please. My tree is non-rebasing which means I cannot just throw the old > tree away and regenerate it from scratch. > >> The last one mmotm-2017-12-22-17-55 seems to have some regression on >> powerpc with respect to ELF loading of binaries (see below). Seems to >> be related to recent MAP_FIXED_SAFE (or MAP_FIXED_NOREPLACE as seen >> now in the code). IIUC (have not been following the series last month) >> MAP_FIXED_NOREPLACE will fail an allocation request if the hint address >> cannot be reserve instead of changing existing mappings. > Correct > >> Is it possible >> that ELF loading needs to be fixed at a higher level to deal with these >> new possible mmap() failures because of MAP_FIXED_NOREPLACE ? > Could you give us more information about the failure please. Debugging > patch from http://lkml.kernel.org/r/20171218091302.GL16951@xxxxxxxxxxxxxx > should help to see what is the clashing VMA. Seems like its re-requesting the same mapping again. [ 23.423642] 9148 (sed): Uhuuh, elf segment at 0000000010030000 requested but the memory is mapped already [ 23.423706] requested [10030000, 10040000] mapped [10030000, 10040000] 100073 anon [ 23.426089] 9151 (sed): Uhuuh, elf segment at 0000000010030000 requested but the memory is mapped already [ 23.426232] requested [10030000, 10040000] mapped [10030000, 10040000] 100073 anon [ 23.429048] 9154 (sed): Uhuuh, elf segment at 0000000010030000 requested but the memory is mapped already [ 23.429196] requested [10030000, 10040000] mapped [10030000, 10040000] 100073 anon [ 23.482766] 9164 (sed): Uhuuh, elf segment at 0000000010030000 requested but the memory is mapped already [ 23.482904] requested [10030000, 10040000] mapped [10030000, 10040000] 100073 anon [ 23.485849] 9167 (sed): Uhuuh, elf segment at 0000000010030000 requested but the memory is mapped already [ 23.485945] requested [10030000, 10040000] mapped [10030000, 10040000] 100073 anon [ 76.041836] 9262 (hostname): Uhuuh, elf segment at 0000000010020000 requested but the memory is mapped already [ 76.041965] requested [10020000, 10030000] mapped [10020000, 10030000] 100073 anon [ 76.207197] 9285 (pkg-config): Uhuuh, elf segment at 0000000010020000 requested but the memory is mapped already [ 76.207326] requested [10020000, 10030000] mapped [10020000, 10030000] 100073 anon [ 76.371073] 9299 (sed): Uhuuh, elf segment at 0000000010030000 requested but the memory is mapped already [ 76.371165] requested [10030000, 10040000] mapped [10030000, 10040000] 100073 anon I have fixed/changed the debug patch a bit diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index d8c5657..a43eccaa 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -372,11 +372,35 @@ static unsigned long elf_map(struct file *filep, unsigned long addr, } else map_addr = vm_mmap(filep, addr, size, prot, type, off); - if ((type & MAP_FIXED_NOREPLACE) && BAD_ADDR(map_addr)) + if ((type & MAP_FIXED_NOREPLACE) && BAD_ADDR(map_addr)) { + struct vm_area_struct *vma; + unsigned long end; + + if (total_size) + end = addr + total_size; + else + end = addr + size; + pr_info("%d (%s): Uhuuh, elf segment at %p requested but the memory is mapped already\n", task_pid_nr(current), current->comm, (void *)addr); + vma = find_vma(current->mm, addr); + if (vma && vma->vm_start <= addr) { + pr_info("requested [%lx, %lx] mapped [%lx, %lx] %lx ", addr, end, + vma->vm_start, vma->vm_end, vma->vm_flags); + if (!vma->vm_file) { + pr_cont("anon\n"); + } else { + char path[512]; + char *p = file_path(vma->vm_file, path, sizeof(path)); + if (IS_ERR(p)) + p = "?"; + pr_cont("\"%s\"\n", kbasename(p)); + } + dump_stack(); + } + } return(map_addr); }
