IMPORTANT NOTE FOR REVIEWERS: v3 of this series is in Andrew's mmotm tree v5.12-rc5-mmotm-2021-03-31-21-27. Muchun Song noticed that Oscar Salvador's series "Make alloc_contig_range handle Hugetlb pages" was also added to that mmotm version. v3 of this series did not take Oscar's changes into account. v4 addresses those omissions. v4 is based on the following: - Start with v5.12-rc5-mmotm-2021-03-31-21-27 - Revert v3 of this series Patch changes from v3: 1 - Trivial context fixup due to cma changes. No functional changes 2, 3 - No change 4, 5 - Changes required due to "Make alloc_contig_range handle Hugetlb pages". Specifically, alloc_and_dissolve_huge_page changes are in need of review. 6 - No change 7 - Fairly straight forward spin_*lock calls to spin_*lock_irq* changes in code from "Make alloc_contig_range handle Hugetlb pages" series. 8 - Trivial change due to context changes. No functional change. If easier to review, I could also provide delta patches on top of patches 4, 5, and 7 of v3. Original cover letter follows: This effort is the result a recent bug report [1]. Syzbot found a potential deadlock in the hugetlb put_page/free_huge_page_path. WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected Since the free_huge_page_path already has code to 'hand off' page free requests to a workqueue, a suggestion was proposed to make the in_irq() detection accurate by always enabling PREEMPT_COUNT [2]. The outcome of that discussion was that the hugetlb put_page path (free_huge_page) path should be properly fixed and safe for all calling contexts. This series is based on v5.12-rc3-mmotm-2021-03-17-22-24. At a high level, the series provides: - Patches 1 & 2 change CMA bitmap mutex to an irq safe spinlock - Patch 3 adds a mutex for proc/sysfs interfaces changing hugetlb counts - Patches 4, 5 & 6 are aimed at reducing lock hold times. To be clear the goal is to eliminate single lock hold times of a long duration. Overall lock hold time is not addressed. - Patch 7 makes hugetlb_lock and subpool lock IRQ safe. It also reverts the code which defers calls to a workqueue if !in_task. - Patch 8 adds some lockdep_assert_held() calls [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@xxxxxxxxxx/ [2] http://lkml.kernel.org/r/20210311021321.127500-1-mike.kravetz@xxxxxxxxxx v3 -> v4 - Add changes needed for the series "Make alloc_contig_range handle Hugetlb pages" v2 -> v3 - Update commit message in patch 1 as suggested by Michal - Do not use spin_lock_irqsave/spin_unlock_irqrestore when we know we are in task context as suggested by Michal - Remove unnecessary INIT_LIST_HEAD() as suggested by Muchun v1 -> v2 - Drop Roman's cma_release_nowait() patches and just change CMA mutex to an IRQ safe spinlock. - Cleanups to variable names, commets and commit messages as suggested by Michal, Oscar, Miaohe and Muchun. - Dropped unnecessary INIT_LIST_HEAD as suggested by Michal and list_del as suggested by Muchun. - Created update_and_free_pages_bulk helper as suggested by Michal. - Rebased on v5.12-rc4-mmotm-2021-03-28-16-37 - Added Acked-by: and Reviewed-by: from v1 RFC -> v1 - Add Roman's cma_release_nowait() patches. This eliminated the need to do a workqueue handoff in hugetlb code. - Use Michal's suggestion to batch pages for freeing. This eliminated the need to recalculate loop control variables when dropping the lock. - Added lockdep_assert_held() calls - Rebased to v5.12-rc3-mmotm-2021-03-17-22-24 Mike Kravetz (8): mm/cma: change cma mutex to irq safe spinlock hugetlb: no need to drop hugetlb_lock to call cma_release hugetlb: add per-hstate mutex to synchronize user adjustments hugetlb: create remove_hugetlb_page() to separate functionality hugetlb: call update_and_free_page without hugetlb_lock hugetlb: change free_pool_huge_page to remove_pool_huge_page hugetlb: make free_huge_page irq safe hugetlb: add lockdep_assert_held() calls for hugetlb_lock include/linux/hugetlb.h | 1 + mm/cma.c | 18 +- mm/cma.h | 2 +- mm/cma_debug.c | 8 +- mm/hugetlb.c | 384 +++++++++++++++++++++------------------- mm/hugetlb_cgroup.c | 8 +- 6 files changed, 218 insertions(+), 203 deletions(-) -- 2.30.2
