On Fri, 16 May 2014, Oleg Nesterov wrote: > On 05/16, Oleg Nesterov wrote: > > > > copy_insn() fails with -EIO if ->readpage == NULL > > In particular, this means that we can not probe the binaries on tmpfs. > This is pity.
Yes, that is a pity: thanks for noticing. > > It seems that the potential fix is trivial, copy_insn() could use > shmem_getpage_gfp(). But, is there any way to figure out that this shmem_getpage_gfp() itself is static: please use shmem_read_mapping_page(mapping, pgoff): inline in linux/shmem_fs.h, calls shmem_read_mapping_page_gfp() in mm/shmem.c (a very few places need to override gfp_mask too: you do not), calls shmem_getpage_gfp(). > inode/mapping/aops/whatever is actually shmem? > > I am looking at shmem_get_inode() and I see nothing which could help, > and shmem_aops/etc are all static. On 3.15 and later, you're in luck: Hannes added bool shmem_mapping(mapping) in his 0cd6144aadd2 "mm + fs: prepare for non-page entries in page cache radix trees"; and I just checked, it builds for "tiny" !CONFIG_SHMEM too. If you're backporting to an earlier kernel, it would probably be best to add in a very small patch, extracting just shmem_mapping() and its linux/mm.h declarations from 0cd6144aadd2. I notice shmem_mapping() checks backing_dev_info, whereas shmem_get_mapping_page_gfp() checks a_ops: no problem in that. But it reminds me that you should test uprobe on SysV SHM when you're done: again I think no problem, but there's an incestuous relationship between shm and shmem that can catch us out when adding such checks. Hugh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
