From: Charan Teja Kalla Date: Tue, 22 Mar 2022 21:46:48 +0000 (-0700) Subject: mm: madvise: skip unmapped vma holes passed to process_madvise X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=27d96f11b0a2f28589485da1bbce3240ab1cedbe;p=linux.git mm: madvise: skip unmapped vma holes passed to process_madvise commit 08095d6310a7ce43256b4251577bc66a25c6e1a6 upstream. The process_madvise() system call is expected to skip holes in vma passed through 'struct iovec' vector list. But do_madvise, which process_madvise() calls for each vma, returns ENOMEM in case of unmapped holes, despite the VMA is processed. Thus process_madvise() should treat ENOMEM as expected and consider the VMA passed to as processed and continue processing other vma's in the vector list. Returning -ENOMEM to user, despite the VMA is processed, will be unable to figure out where to start the next madvise. Link: https://lkml.kernel.org/r/4f091776142f2ebf7b94018146de72318474e686.1647008754.git.quic_charante@quicinc.com Fixes: ecb8ac8b1f14("mm/madvise: introduce process_madvise() syscall: an external memory hinting API") Signed-off-by: Charan Teja Kalla Cc: David Rientjes Cc: Michal Hocko Cc: Minchan Kim Cc: Nadav Amit Cc: Stephen Rothwell Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/mm/madvise.c b/mm/madvise.c index 0734db8d53a7a..b215f0e2ab409 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1287,9 +1287,16 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, while (iov_iter_count(&iter)) { iovec = iov_iter_iovec(&iter); + /* + * do_madvise returns ENOMEM if unmapped holes are present + * in the passed VMA. process_madvise() is expected to skip + * unmapped holes passed to it in the 'struct iovec' list + * and not fail because of them. Thus treat -ENOMEM return + * from do_madvise as valid and continue processing. + */ ret = do_madvise(mm, (unsigned long)iovec.iov_base, iovec.iov_len, behavior); - if (ret < 0) + if (ret < 0 && ret != -ENOMEM) break; iov_iter_advance(&iter, iovec.iov_len); }