Messages in this thread Patch in this message | | | Date | Mon, 25 Nov 2013 14:13:28 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] procfs: also fix proc_reg_get_unmapped_area() for !MMU case |
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On Mon, 25 Nov 2013 16:22:31 +0000 "Jan Beulich" <JBeulich@suse.com> wrote:
> Commit fad1a86e ("procfs: call default get_unmapped_area on MMU-present > architectures"), as its title says, took care of only the MMU case, > leaving the !MMU side still in the regressed state (returning -EIO in > all cases where pde->proc_fops->get_unmapped_area is NULL).
The changelog is rather mystifying unless the reader goes off and finds the fad1a86e changelog, so let's do that for them by adding this:
From the fad1a86e changelog:
: Commit c4fe24485729 ("sparc: fix PCI device proc file mmap(2)") added : proc_reg_get_unmapped_area in proc_reg_file_ops and : proc_reg_file_ops_no_compat, by which now mmap always returns EIO if : get_unmapped_area method is not defined for the target procfs file, which : causes regression of mmap on /proc/vmcore. : : To address this issue, like get_unmapped_area(), call default : current->mm->get_unmapped_area on MMU-present architectures if : pde->proc_fops->get_unmapped_area, i.e. the one in actual file operation : in the procfs file, is not defined.
> Signed-off-by: Jan Beulich <jbeulich@suse.com> > Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> > Cc: Alexey Dobriyan <adobriyan@gmail.com> > Cc: David S. Miller <davem@davemloft.net>
I tagged this with
Cc: <stable@vger.kernel.org> [3.12.x]
OK?
> +++ 3.13-rc1-proc-get-unmapped-area/fs/proc/inode.c > @@ -292,16 +292,19 @@ proc_reg_get_unmapped_area(struct file * > { > struct proc_dir_entry *pde = PDE(file_inode(file)); > unsigned long rv = -EIO; > - unsigned long (*get_area)(struct file *, unsigned long, unsigned long, > - unsigned long, unsigned long) = NULL; > + > if (use_pde(pde)) { > + typeof(proc_reg_get_unmapped_area) *get_area > #ifdef CONFIG_MMU > - get_area = current->mm->get_unmapped_area; > + = pde->proc_fops->get_unmapped_area > + ?: current->mm->get_unmapped_area; > +#else > + = pde->proc_fops->get_unmapped_area; > #endif > - if (pde->proc_fops->get_unmapped_area) > - get_area = pde->proc_fops->get_unmapped_area; > - if (get_area) > - rv = get_area(file, orig_addr, len, pgoff, flags); > + > + rv = get_area > + ? get_area(file, orig_addr, len, pgoff, flags) > + : orig_addr; > unuse_pde(pde); > } > return rv;
That function has gone from bad to worse :(
How does this version look?
It would be acceptable and beneficial to create a new get_unmapped_area_t.
: static unsigned long : proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr, : unsigned long len, unsigned long pgoff, : unsigned long flags) : { : struct proc_dir_entry *pde = PDE(file_inode(file)); : unsigned long rv = -EIO; : : if (use_pde(pde)) { : typeof(proc_reg_get_unmapped_area) *get_area; : : get_area = pde->proc_fops->get_unmapped_area; : #ifdef CONFIG_MMU : if (!get_area) : get_area = current->mm->get_unmapped_area; : #endif : : if (get_area) : rv = get_area(file, orig_addr, len, pgoff, flags); : else : rv = orig_addr; : unuse_pde(pde); : } : return rv; : }
--- a/fs/proc/inode.c~procfs-also-fix-proc_reg_get_unmapped_area-for-mmu-case-fix +++ a/fs/proc/inode.c @@ -294,17 +294,18 @@ proc_reg_get_unmapped_area(struct file * unsigned long rv = -EIO; if (use_pde(pde)) { - typeof(proc_reg_get_unmapped_area) *get_area + typeof(proc_reg_get_unmapped_area) *get_area; + + get_area = pde->proc_fops->get_unmapped_area; #ifdef CONFIG_MMU - = pde->proc_fops->get_unmapped_area - ?: current->mm->get_unmapped_area; -#else - = pde->proc_fops->get_unmapped_area; + if (!get_area) + get_area = current->mm->get_unmapped_area; #endif - rv = get_area - ? get_area(file, orig_addr, len, pgoff, flags) - : orig_addr; + if (get_area) + rv = get_area(file, orig_addr, len, pgoff, flags); + else + rv = orig_addr; unuse_pde(pde); } return rv; _
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