Hugh Dickins wrote: > Better late than never, I've at last reviewed the madvise vma merging > going into 2.6.13. Remove a pointless check and fix two little bugs - > a simple test (with /proc/<pid>/maps hacked to show ReadHints) showed > both mismerges in practice: though being madvise, neither was disastrous. > > 1. Correct placement of the success label in madvise_behavior: as in > mprotect_fixup and mlock_fixup, it is necessary to update vm_flags > when vma_merge succeeds (to handle the exceptional Case 8 noted in > the comments above vma_merge itself). > > 2. Correct initial value of prev when starting part way into a vma: as > in sys_mprotect and do_mlock, it needs to be set to vma in this case > (vma_merge handles only that minimum of cases shown in its comments). > > 3. If find_vma_prev sets prev, then the vma it returns is prev->vm_next, > so it's pointless to make that same assignment again in sys_madvise.
Acknowledge corrections 1 and 3 readily. Treated vma_merge as block box that can handle all cases. Motivation for pointless case 3 is to skip holes and did not notice that has been covered. Thanks for corrections. > (vma_merge handles only that minimum of cases shown in its comments). > Correction 2 is tricky. Sometimes it merges similar to case 3, misses a needed split, where after the fix we can get case 4 merge. If that is what you are saying, we are in agreement. Otherwise, can you explain the real problem? Thanks, Prasanna. - 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/
