On Fri, Apr 20, 2012 at 12:18:43PM -0700, Linus Torvalds wrote:
> The *bigger* annoyance is actually "do_mmap()", which does a
> do_munmap() as part of it, so it needs the same cleanup too.
So does a bunch of other places. Let me dig out the call graph circa
3.3.0... Here is the relevant part:
do_munmap() -
<- pfm_do_munmap() <- pfm_remove_smpl_mapping() which grabs mmap_sem excl
<- 64_munmap(2) which grabs mmap_sem excl
<- kvm_arch_commit_memory_region() which grabs mmap_sem excl
<- i810_unmap_buffer() which grabs mmap_sem excl
<- aio_free_ring() which grabs mmap_sem excl
<- elf_map() which grabs mmap_sem excl
<- [flat] load_flat_file() --- BUG HERE
<- shmdt(2) which grabs mmap_sem excl
<- brk(2) which grabs mmap_sem excl
<- mmap_region() [see below]
<- munmap(2) which grabs mmap_sem excl
<- do_brk() [see below]
<- move_vma()
<- mremap_to() <- do_mremap() [see below]
<- do_mremap() [see below]
<- mremap_to() <- do_mremap() [see below]
<- do_mremap() [see below]
do_brk() -
<- brk(2) which grabs mmap_sem excl
<- [ia32_aout] set_brk() which grabs mmap_sem excl
<- [ia32_aout] load_aout_binary() which grabs mmap_sem excl
<- [ia32_aout] load_aout_library() which grabs mmap_sem excl
<- [aout] set_brk() which grabs mmap_sem excl
<- [aout] load_aout_binary() which grabs mmap_sem excl
<- [aout] load_aout_library() which grabs mmap_sem excl
<- [elf] set_brk() which grabs mmap_sem excl
<- [elf] load_elf_interp() which grabs mmap_sem excl
<- [elf] load_elf_library() which grabs mmap_sem excl
mmap_region() -
<- remap_file_pages(2) which grabs mmap_sem excl
<- do_mmap_pgoff() [see below]
<- [tile] arch_setup_additional_pages() which grabs mmap_sem excl
(a bit too late, BTW, but not for this one)
do_mmap_pgoff() -
<- do_mmap() [see below]
<- mmap_pgoff(2) which grabs mmap_sem excl
do_mmap() -
<- shmat(2) which grabs mmap_sem excl
<- aio_setup_ring() which grabs mmap_sem excl [NB: only because ctx->mm == current->mm]
<- kvm_arch_prepare_memory_region() which grabs mmap_sem excl
<- drm_mapbufs() which grabs mmap_sem excl
<- exynos_drm_gem_mmap_ioctl() which grabs mmap_sem excl
<- i810_map_buffer() which grabs mmap_sem excl [NB: racy changes of ->f_op]
<- i915_gem_mmap_ioctl() which grabs mmap_sem excl
<- [tile] single_step_once() which grabs mmap_sem excl
<- [elf] elf_map() which grabs mmap_sem excl
<- [elf] load_elf_binary() which grabs mmap_sem excl
<- [elf_fdpic] load_elf_fdpic_binary() which grabs mmap_sem excl
<- [elf_fdpic] elf_fdpic_map_file_constdisp_on_uclinux() which grabs mmap_sem excl
<- [elf_fdpic] elf_fdpic_map_file_by_direct_mmap() which grabs mmap_sem excl
<- [aout] load_aout_binary() which grabs mmap_sem excl
<- [aout] load_aout_library() which grabs mmap_sem excl
<- [ia32_aout] load_aout_binary() which grabs mmap_sem excl
<- [ia32_aout] load_aout_library() which grabs mmap_sem excl
<- [flat] load_flat_file() which grabs mmap_sem excl
<- [som] map_som_binary() which grabs mmap_sem excl
do_mremap() -
<- mremap(2) which grabs mmap_sem excl
(bug mentioned re load_flat_file() is still there, but it's irrelevant
for our purposes - no ->mmap_sem held by caller of do_munmap()). That's
a metric arseload of sites to propagate that thing to...
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