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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org, Muhammad Usama Anjum , "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3059; i=david@kernel.org; h=from:subject:message-id; bh=jIZ4aj6oO0T8O1iDgAYwxVUGJ5PVlOxvrE64yrDPOpw=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLKebs+YcELBdt666LezdhU52py4HZm8/dli+Q03o4qWM xRWFxqs6ihlYRDjYJAVU2QJCr5v8PLlutpqNz5mmDmsTCBDGLg4BWAianqMDO/D2137GiO5DPhs zh344W9+yLuP8c+LXNmID1+Yjs5d08LI8PXN7dVm34SkfnwM6C++9qtg/ZrPP8T2TW/qe7h+anf SCx4A X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Stat-Signature: faamezuxfy4c6m6etdi7po1zwoizu5wx X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: F2A5880003 X-Rspam-User: X-HE-Tag: 1793440005-9554 X-HE-Meta: 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 F0Lc45v+ QOfO7rxUlIaDs7ltejBhjpMIHCcnnr+1D+mHKdFtSuRFTPU5q2MT9VDB0ELKvAcv7reoxH1g7LVUX2axGJE7iZlYnjrn7WAaUPeby49VO/9Q7TAk1wmaS2u+OLyMJ49Ds/4S4CgiTyHatagAyHwO4Opyh7q0/t1kw0XdBUxD2tQGewqbB8JAmGRvsV8/f4IN5NAwyovyWWMZqBaXr/tzmy63Yfkpbx2pSMwsYuSX6TPWmuP9mzgBkWFhXpmhykS9xcLzAZdjhgfqtrF+4XoC8LAm2DK9k2716BkWomQm9xbJszUFaSZ7oJVgo0b5AxDy4hPqiU0jzYExuJdLy9/LS2tQyq5HPelkMASykFF1tkNlC8156zfCZHMZLUt9rCctf6MjiVgd3NN7B2RkLoi9mAKa3OkSQOsU63IZZCq5dMAr7sIsSNnSqwjXwuUbVhytYTyXLAQbriiiuB/RqIR9w3piD7OIpU38qQmmyf7rn5bedo5M= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 UFFDIO_REGISTER can replace MISSING or MINOR tracking without waking faults that are already queued. For example, switching an anonymous range from MISSING to WP leaves a missing-fault waiter asleep until userspace explicitly wakes it. When a registration change removes a UFFD mode, wake waiters in the affected interval after updating the VMA. The VMA is write-locked at this point, so no new faults can queue under the old modes and woken threads cannot retry until mmap_write_unlock(). Waiters for retained modes in the same interval may also wake and refault. The hang reproduces for MISSING-to-WP and MINOR-to-MISSING transitions, with both read and unread fault events. Fixes: 63b2d4174c4a ("userfaultfd: wp: add the writeprotect API to userfaultfd ioctl") Cc: stable@vger.kernel.org Reviewed-by: Gregory Price (Meta) Tested-by: Gregory Price (Meta) Signed-off-by: Gregory Price (Meta) Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Lorenzo Stoakes (ARM) Tested-by: Muhammad Usama Anjum Signed-off-by: David Hildenbrand (Arm) --- mm/userfaultfd.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index be630674fda9b..03f1b15bfe63e 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -2270,6 +2270,9 @@ static struct vm_area_struct *userfaultfd_clear_vma(struct vma_iterator *vmi, return ret; } +static void wake_userfault_range(struct userfaultfd_ctx *ctx, + unsigned long start, unsigned long end); + /* Assumes mmap write lock taken, and mm_struct pinned. */ static int userfaultfd_register_range(struct userfaultfd_ctx *ctx, struct vm_area_struct *vma, @@ -2287,6 +2290,8 @@ static int userfaultfd_register_range(struct userfaultfd_ctx *ctx, prev = vma; for_each_vma_range(vmi, vma, end) { + const bool any_mode_removed = vma->vm_flags & __VM_UFFD_FLAGS & ~vm_flags; + cond_resched(); VM_WARN_ON_ONCE(!vma_can_userfault(vma, vm_flags, wp_async)); @@ -2332,6 +2337,10 @@ static int userfaultfd_register_range(struct userfaultfd_ctx *ctx, */ userfaultfd_set_ctx(vma, ctx, vm_flags); + /* Retry faults for removed modes while the VMA is write-locked. */ + if (any_mode_removed) + wake_userfault_range(ctx, start, vma_end); + if (vma_is_hugetlb(vma) && uffd_disable_huge_pmd_share(vma)) hugetlb_unshare_all_pmds(vma); @@ -3648,6 +3657,17 @@ static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx, __wake_userfault(ctx, range); } +static void wake_userfault_range(struct userfaultfd_ctx *ctx, + unsigned long start, unsigned long end) +{ + struct userfaultfd_wake_range range = { + .start = start, + .len = end - start, + }; + + wake_userfault(ctx, &range); +} + static __always_inline int validate_unaligned_range( struct mm_struct *mm, __u64 start, __u64 len) { -- 2.43.0