linux.git/mm, branch v6.6-rc2 Linux kernel source tree vm: fix move_vma() memory accounting being off 2023-09-16T22:23:31+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-09-16T19:31:42+00:00 3cec50490969afd4a76ccee441f747d869ccff77 Commit 408579cd627a ("mm: Update do_vmi_align_munmap() return semantics") seems to have updated one of the callers of do_vmi_munmap() incorrectly: it used to check for the error case (which didn't change: negative means error). That commit changed the check to the success case (which did change: before that commit, 0 was success, and 1 was "success and lock downgraded". After the change, it's always 0 for success, and the lock will have been released if requested). This didn't change any actual VM behavior _except_ for memory accounting when 'VM_ACCOUNT' was set on the vma. Which made the wrong return value test fairly subtle, since everything continues to work. Or rather - it continues to work but the "Committed memory" accounting goes all wonky (Committed_AS value in /proc/meminfo), and depending on settings that then causes problems much much later as the VM relies on bogus statistics for its heuristics. Revert that one line of the change back to the original logic. Fixes: 408579cd627a ("mm: Update do_vmi_align_munmap() return semantics") Reported-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de> Reported-bisected-and-tested-by: Michael Labiuk <michael.labiuk@virtuozzo.com> Cc: Bagas Sanjaya <bagasdotme@gmail.com> Cc: Liam R. Howlett <Liam.Howlett@oracle.com> Link: https://lore.kernel.org/all/1694366957@msgid.manchmal.in-ulm.de/ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Commit 408579cd627a ("mm: Update do_vmi_align_munmap() return
semantics") seems to have updated one of the callers of do_vmi_munmap()
incorrectly: it used to check for the error case (which didn't
change: negative means error).

That commit changed the check to the success case (which did change:
before that commit, 0 was success, and 1 was "success and lock
downgraded".  After the change, it's always 0 for success, and the lock
will have been released if requested).

This didn't change any actual VM behavior _except_ for memory accounting
when 'VM_ACCOUNT' was set on the vma.  Which made the wrong return value
test fairly subtle, since everything continues to work.

Or rather - it continues to work but the "Committed memory" accounting
goes all wonky (Committed_AS value in /proc/meminfo), and depending on
settings that then causes problems much much later as the VM relies on
bogus statistics for its heuristics.

Revert that one line of the change back to the original logic.

Fixes: 408579cd627a ("mm: Update do_vmi_align_munmap() return semantics")
Reported-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
Reported-bisected-and-tested-by: Michael Labiuk <michael.labiuk@virtuozzo.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Link: https://lore.kernel.org/all/1694366957@msgid.manchmal.in-ulm.de/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge tag 'loongarch-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson 2023-09-08T19:16:52+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-09-08T19:16:52+00:00 12952b6bbd36b372345f179f1a85576c5924d425 Pull LoongArch updates from Huacai Chen: - Allow usage of LSX/LASX in the kernel, and use them for SIMD-optimized RAID5/RAID6 routines - Add Loongson Binary Translation (LBT) extension support - Add basic KGDB & KDB support - Add building with kcov coverage - Add KFENCE (Kernel Electric-Fence) support - Add KASAN (Kernel Address Sanitizer) support - Some bug fixes and other small changes - Update the default config file * tag 'loongarch-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson: (25 commits) LoongArch: Update Loongson-3 default config file LoongArch: Add KASAN (Kernel Address Sanitizer) support LoongArch: Simplify the processing of jumping new kernel for KASLR kasan: Add (pmd|pud)_init for LoongArch zero_(pud|p4d)_populate process kasan: Add __HAVE_ARCH_SHADOW_MAP to support arch specific mapping LoongArch: Add KFENCE (Kernel Electric-Fence) support LoongArch: Get partial stack information when providing regs parameter LoongArch: mm: Add page table mapped mode support for virt_to_page() kfence: Defer the assignment of the local variable addr LoongArch: Allow building with kcov coverage LoongArch: Provide kaslr_offset() to get kernel offset LoongArch: Add basic KGDB & KDB support LoongArch: Add Loongson Binary Translation (LBT) extension support raid6: Add LoongArch SIMD recovery implementation raid6: Add LoongArch SIMD syndrome calculation LoongArch: Add SIMD-optimized XOR routines LoongArch: Allow usage of LSX/LASX in the kernel LoongArch: Define symbol 'fault' as a local label in fpu.S LoongArch: Adjust {copy, clear}_user exception handler behavior LoongArch: Use static defined zero page rather than allocated ... 
Pull LoongArch updates from Huacai Chen:

 - Allow usage of LSX/LASX in the kernel, and use them for
   SIMD-optimized RAID5/RAID6 routines

 - Add Loongson Binary Translation (LBT) extension support

 - Add basic KGDB & KDB support

 - Add building with kcov coverage

 - Add KFENCE (Kernel Electric-Fence) support

 - Add KASAN (Kernel Address Sanitizer) support

 - Some bug fixes and other small changes

 - Update the default config file

* tag 'loongarch-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson: (25 commits)
  LoongArch: Update Loongson-3 default config file
  LoongArch: Add KASAN (Kernel Address Sanitizer) support
  LoongArch: Simplify the processing of jumping new kernel for KASLR
  kasan: Add (pmd|pud)_init for LoongArch zero_(pud|p4d)_populate process
  kasan: Add __HAVE_ARCH_SHADOW_MAP to support arch specific mapping
  LoongArch: Add KFENCE (Kernel Electric-Fence) support
  LoongArch: Get partial stack information when providing regs parameter
  LoongArch: mm: Add page table mapped mode support for virt_to_page()
  kfence: Defer the assignment of the local variable addr
  LoongArch: Allow building with kcov coverage
  LoongArch: Provide kaslr_offset() to get kernel offset
  LoongArch: Add basic KGDB & KDB support
  LoongArch: Add Loongson Binary Translation (LBT) extension support
  raid6: Add LoongArch SIMD recovery implementation
  raid6: Add LoongArch SIMD syndrome calculation
  LoongArch: Add SIMD-optimized XOR routines
  LoongArch: Allow usage of LSX/LASX in the kernel
  LoongArch: Define symbol 'fault' as a local label in fpu.S
  LoongArch: Adjust {copy, clear}_user exception handler behavior
  LoongArch: Use static defined zero page rather than allocated
  ...
kasan: Add (pmd|pud)_init for LoongArch zero_(pud|p4d)_populate process 2023-09-06T14:54:16+00:00 Qing Zhang zhangqing@loongson.cn 2023-09-06T14:54:16+00:00 fb6d5c1d99ab6958c5e284f7aa5f0cc553f0268c LoongArch populates pmd/pud with invalid_pmd_table/invalid_pud_table in pagetable_init, So pmd_init/pud_init(p) is required, define them as __weak in mm/kasan/init.c, like mm/sparse-vmemmap.c. Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Signed-off-by: Qing Zhang <zhangqing@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> 
LoongArch populates pmd/pud with invalid_pmd_table/invalid_pud_table in
pagetable_init, So pmd_init/pud_init(p) is required, define them as __weak
in mm/kasan/init.c, like mm/sparse-vmemmap.c.

Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
kasan: Add __HAVE_ARCH_SHADOW_MAP to support arch specific mapping 2023-09-06T14:54:16+00:00 Qing Zhang zhangqing@loongson.cn 2023-09-06T14:54:16+00:00 9b04c764af18a1dab6d48ca0671f70cdcccf90a2 MIPS, LoongArch and some other architectures have many holes between different segments and the valid address space (256T available) is insufficient to map all these segments to kasan shadow memory with the common formula provided by kasan core. So we need architecture specific mapping formulas to ensure different segments are mapped individually, and only limited space lengths of those specific segments are mapped to shadow. Therefore, when the incoming address is converted to a shadow, we need to add a condition to determine whether it is valid. Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Signed-off-by: Qing Zhang <zhangqing@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> 
MIPS, LoongArch and some other architectures have many holes between
different segments and the valid address space (256T available) is
insufficient to map all these segments to kasan shadow memory with the
common formula provided by kasan core. So we need architecture specific
mapping formulas to ensure different segments are mapped individually,
and only limited space lengths of those specific segments are mapped to
shadow.

Therefore, when the incoming address is converted to a shadow, we need
to add a condition to determine whether it is valid.

Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
kfence: Defer the assignment of the local variable addr 2023-09-06T14:53:55+00:00 Enze Li lienze@kylinos.cn 2023-09-06T14:53:55+00:00 ec9fee79d48f2f05cb1b95dc901071aa3670f228 The LoongArch architecture is different from other architectures. It needs to update __kfence_pool during arch_kfence_init_pool(). This patch modifies the assignment location of the local variable addr in the kfence_init_pool() function to support the case of updating __kfence_pool in arch_kfence_init_pool(). Acked-by: Marco Elver <elver@google.com> Signed-off-by: Enze Li <lienze@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> 
The LoongArch architecture is different from other architectures. It
needs to update __kfence_pool during arch_kfence_init_pool().

This patch modifies the assignment location of the local variable addr
in the kfence_init_pool() function to support the case of updating
__kfence_pool in arch_kfence_init_pool().

Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Enze Li <lienze@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Merge tag 'mm-hotfixes-stable-2023-09-05-11-51' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 2023-09-05T19:22:39+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-09-05T19:22:39+00:00 3c5c9b7cfd7d2a2b1e32c2284c82164c1aaa919f Pull misc fixes from Andrew Morton: "Seven hotfixes. Four are cc:stable and the remainder pertain to issues which were introduced in the current merge window" * tag 'mm-hotfixes-stable-2023-09-05-11-51' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: sparc64: add missing initialization of folio in tlb_batch_add() mm: memory-failure: use rcu lock instead of tasklist_lock when collect_procs() revert "memfd: improve userspace warnings for missing exec-related flags". rcu: dump vmalloc memory info safely mm/vmalloc: add a safer version of find_vm_area() for debug tools/mm: fix undefined reference to pthread_once memcontrol: ensure memcg acquired by id is properly set up 
Pull misc fixes from Andrew Morton:
 "Seven hotfixes. Four are cc:stable and the remainder pertain to issues
  which were introduced in the current merge window"

* tag 'mm-hotfixes-stable-2023-09-05-11-51' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  sparc64: add missing initialization of folio in tlb_batch_add()
  mm: memory-failure: use rcu lock instead of tasklist_lock when collect_procs()
  revert "memfd: improve userspace warnings for missing exec-related flags".
  rcu: dump vmalloc memory info safely
  mm/vmalloc: add a safer version of find_vm_area() for debug
  tools/mm: fix undefined reference to pthread_once
  memcontrol: ensure memcg acquired by id is properly set up
mm: memory-failure: use rcu lock instead of tasklist_lock when collect_procs() 2023-09-05T18:11:52+00:00 Tong Tiangen tongtiangen@huawei.com 2023-08-28T02:25:27+00:00 d256d1cd8da1cbc4615de69df71c87ce623fec2f We found a softlock issue in our test, analyzed the logs, and found that the relevant CPU call trace as follows: CPU0: _do_fork -> copy_process() -> write_lock_irq(&tasklist_lock) //Disable irq,waiting for //tasklist_lock CPU1: wp_page_copy() ->pte_offset_map_lock() -> spin_lock(&page->ptl); //Hold page->ptl -> ptep_clear_flush() -> flush_tlb_others() ... -> smp_call_function_many() -> arch_send_call_function_ipi_mask() -> csd_lock_wait() //Waiting for other CPUs respond //IPI CPU2: collect_procs_anon() -> read_lock(&tasklist_lock) //Hold tasklist_lock ->for_each_process(tsk) -> page_mapped_in_vma() -> page_vma_mapped_walk() -> map_pte() ->spin_lock(&page->ptl) //Waiting for page->ptl We can see that CPU1 waiting for CPU0 respond IPI，CPU0 waiting for CPU2 unlock tasklist_lock, CPU2 waiting for CPU1 unlock page->ptl. As a result, softlockup is triggered. For collect_procs_anon(), what we're doing is task list iteration, during the iteration, with the help of call_rcu(), the task_struct object is freed only after one or more grace periods elapse. the logic as follows: release_task() -> __exit_signal() -> __unhash_process() -> list_del_rcu() -> put_task_struct_rcu_user() -> call_rcu(&task->rcu, delayed_put_task_struct) delayed_put_task_struct() -> put_task_struct() -> if (refcount_sub_and_test()) __put_task_struct() -> free_task() Therefore, under the protection of the rcu lock, we can safely use get_task_struct() to ensure a safe reference to task_struct during the iteration. By removing the use of tasklist_lock in task list iteration, we can break the softlock chain above. The same logic can also be applied to: - collect_procs_file() - collect_procs_fsdax() - collect_procs_ksm() Link: https://lkml.kernel.org/r/20230828022527.241693-1-tongtiangen@huawei.com Signed-off-by: Tong Tiangen <tongtiangen@huawei.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
We found a softlock issue in our test, analyzed the logs, and found that
the relevant CPU call trace as follows:

CPU0:
  _do_fork
    -> copy_process()
      -> write_lock_irq(&tasklist_lock)  //Disable irq,waiting for
      					 //tasklist_lock

CPU1:
  wp_page_copy()
    ->pte_offset_map_lock()
      -> spin_lock(&page->ptl);        //Hold page->ptl
    -> ptep_clear_flush()
      -> flush_tlb_others() ...
        -> smp_call_function_many()
          -> arch_send_call_function_ipi_mask()
            -> csd_lock_wait()         //Waiting for other CPUs respond
	                               //IPI

CPU2:
  collect_procs_anon()
    -> read_lock(&tasklist_lock)       //Hold tasklist_lock
      ->for_each_process(tsk)
        -> page_mapped_in_vma()
          -> page_vma_mapped_walk()
	    -> map_pte()
              ->spin_lock(&page->ptl)  //Waiting for page->ptl

We can see that CPU1 waiting for CPU0 respond IPI，CPU0 waiting for CPU2
unlock tasklist_lock, CPU2 waiting for CPU1 unlock page->ptl. As a result,
softlockup is triggered.

For collect_procs_anon(), what we're doing is task list iteration, during
the iteration, with the help of call_rcu(), the task_struct object is freed
only after one or more grace periods elapse. the logic as follows:

release_task()
  -> __exit_signal()
    -> __unhash_process()
      -> list_del_rcu()

  -> put_task_struct_rcu_user()
    -> call_rcu(&task->rcu, delayed_put_task_struct)

delayed_put_task_struct()
  -> put_task_struct()
  -> if (refcount_sub_and_test())
     	__put_task_struct()
          -> free_task()

Therefore, under the protection of the rcu lock, we can safely use
get_task_struct() to ensure a safe reference to task_struct during the
iteration.

By removing the use of tasklist_lock in task list iteration, we can break
the softlock chain above.

The same logic can also be applied to:
 - collect_procs_file()
 - collect_procs_fsdax()
 - collect_procs_ksm()

Link: https://lkml.kernel.org/r/20230828022527.241693-1-tongtiangen@huawei.com
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
revert "memfd: improve userspace warnings for missing exec-related flags". 2023-09-05T18:11:52+00:00 Andrew Morton akpm@linux-foundation.org 2023-09-02T22:59:31+00:00 2562d67b1bdf91c7395b0225d60fdeb26b4bc5a0 This warning is telling userspace developers to pass MFD_EXEC and MFD_NOEXEC_SEAL to memfd_create(). Commit 434ed3350f57 ("memfd: improve userspace warnings for missing exec-related flags") made the warning more frequent and visible in the hope that this would accelerate the fixing of errant userspace. But the overall effect is to generate far too much dmesg noise. Fixes: 434ed3350f57 ("memfd: improve userspace warnings for missing exec-related flags") Reported-by: Damian Tometzki <dtometzki@fedoraproject.org> Closes: https://lkml.kernel.org/r/ZPFzCSIgZ4QuHsSC@fedora.fritz.box Cc: Aleksa Sarai <cyphar@cyphar.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Daniel Verkamp <dverkamp@chromium.org> Cc: Jeff Xu <jeffxu@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Shuah Khan <shuah@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
This warning is telling userspace developers to pass MFD_EXEC and
MFD_NOEXEC_SEAL to memfd_create().  Commit 434ed3350f57 ("memfd: improve
userspace warnings for missing exec-related flags") made the warning more
frequent and visible in the hope that this would accelerate the fixing of
errant userspace.

But the overall effect is to generate far too much dmesg noise.

Fixes: 434ed3350f57 ("memfd: improve userspace warnings for missing exec-related flags")
Reported-by: Damian Tometzki <dtometzki@fedoraproject.org>
Closes: https://lkml.kernel.org/r/ZPFzCSIgZ4QuHsSC@fedora.fritz.box
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Verkamp <dverkamp@chromium.org>
Cc: Jeff Xu <jeffxu@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Merge tag 'mm-stable-2023-09-04-14-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 2023-09-05T17:56:27+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-09-05T17:56:27+00:00 5eea5820c7340d39e56e169e1b87199391105f6b Pull more MM updates from Andrew Morton: - Stefan Roesch has added ksm statistics to /proc/pid/smaps - Also a number of singleton patches, mainly cleanups and leftovers * tag 'mm-stable-2023-09-04-14-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: mm/kmemleak: move up cond_resched() call in page scanning loop mm: page_alloc: remove stale CMA guard code MAINTAINERS: add rmap.h to mm entry rmap: remove anon_vma_link() nommu stub proc/ksm: add ksm stats to /proc/pid/smaps mm/hwpoison: rename hwp_walk* to hwpoison_walk* mm: memory-failure: add PageOffline() check 
Pull more MM updates from Andrew Morton:

 - Stefan Roesch has added ksm statistics to /proc/pid/smaps

 - Also a number of singleton patches, mainly cleanups and leftovers

* tag 'mm-stable-2023-09-04-14-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  mm/kmemleak: move up cond_resched() call in page scanning loop
  mm: page_alloc: remove stale CMA guard code
  MAINTAINERS: add rmap.h to mm entry
  rmap: remove anon_vma_link() nommu stub
  proc/ksm: add ksm stats to /proc/pid/smaps
  mm/hwpoison: rename hwp_walk* to hwpoison_walk*
  mm: memory-failure: add PageOffline() check
rcu: dump vmalloc memory info safely 2023-09-05T17:13:45+00:00 Zqiang qiang.zhang1211@gmail.com 2023-09-04T18:08:05+00:00 c83ad36a18c02c0f51280b50272327807916987f Currently, for double invoke call_rcu(), will dump rcu_head objects memory info, if the objects is not allocated from the slab allocator, the vmalloc_dump_obj() will be invoke and the vmap_area_lock spinlock need to be held, since the call_rcu() can be invoked in interrupt context, therefore, there is a possibility of spinlock deadlock scenarios. And in Preempt-RT kernel, the rcutorture test also trigger the following lockdep warning: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 1, name: swapper/0 preempt_count: 1, expected: 0 RCU nest depth: 1, expected: 1 3 locks held by swapper/0/1: #0: ffffffffb534ee80 (fullstop_mutex){+.+.}-{4:4}, at: torture_init_begin+0x24/0xa0 #1: ffffffffb5307940 (rcu_read_lock){....}-{1:3}, at: rcu_torture_init+0x1ec7/0x2370 #2: ffffffffb536af40 (vmap_area_lock){+.+.}-{3:3}, at: find_vmap_area+0x1f/0x70 irq event stamp: 565512 hardirqs last enabled at (565511): [<ffffffffb379b138>] __call_rcu_common+0x218/0x940 hardirqs last disabled at (565512): [<ffffffffb5804262>] rcu_torture_init+0x20b2/0x2370 softirqs last enabled at (399112): [<ffffffffb36b2586>] __local_bh_enable_ip+0x126/0x170 softirqs last disabled at (399106): [<ffffffffb43fef59>] inet_register_protosw+0x9/0x1d0 Preemption disabled at: [<ffffffffb58040c3>] rcu_torture_init+0x1f13/0x2370 CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 6.5.0-rc4-rt2-yocto-preempt-rt+ #15 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x68/0xb0 dump_stack+0x14/0x20 __might_resched+0x1aa/0x280 ? __pfx_rcu_torture_err_cb+0x10/0x10 rt_spin_lock+0x53/0x130 ? find_vmap_area+0x1f/0x70 find_vmap_area+0x1f/0x70 vmalloc_dump_obj+0x20/0x60 mem_dump_obj+0x22/0x90 __call_rcu_common+0x5bf/0x940 ? debug_smp_processor_id+0x1b/0x30 call_rcu_hurry+0x14/0x20 rcu_torture_init+0x1f82/0x2370 ? __pfx_rcu_torture_leak_cb+0x10/0x10 ? __pfx_rcu_torture_leak_cb+0x10/0x10 ? __pfx_rcu_torture_init+0x10/0x10 do_one_initcall+0x6c/0x300 ? debug_smp_processor_id+0x1b/0x30 kernel_init_freeable+0x2b9/0x540 ? __pfx_kernel_init+0x10/0x10 kernel_init+0x1f/0x150 ret_from_fork+0x40/0x50 ? __pfx_kernel_init+0x10/0x10 ret_from_fork_asm+0x1b/0x30 </TASK> The previous patch fixes this by using the deadlock-safe best-effort version of find_vm_area. However, in case of failure print the fact that the pointer was a vmalloc pointer so that we print at least something. Link: https://lkml.kernel.org/r/20230904180806.1002832-2-joel@joelfernandes.org Fixes: 98f180837a89 ("mm: Make mem_dump_obj() handle vmalloc() memory") Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Reported-by: Zhen Lei <thunder.leizhen@huaweicloud.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
Currently, for double invoke call_rcu(), will dump rcu_head objects memory
info, if the objects is not allocated from the slab allocator, the
vmalloc_dump_obj() will be invoke and the vmap_area_lock spinlock need to
be held, since the call_rcu() can be invoked in interrupt context,
therefore, there is a possibility of spinlock deadlock scenarios.

And in Preempt-RT kernel, the rcutorture test also trigger the following
lockdep warning:

BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 1, name: swapper/0
preempt_count: 1, expected: 0
RCU nest depth: 1, expected: 1
3 locks held by swapper/0/1:
 #0: ffffffffb534ee80 (fullstop_mutex){+.+.}-{4:4}, at: torture_init_begin+0x24/0xa0
 #1: ffffffffb5307940 (rcu_read_lock){....}-{1:3}, at: rcu_torture_init+0x1ec7/0x2370
 #2: ffffffffb536af40 (vmap_area_lock){+.+.}-{3:3}, at: find_vmap_area+0x1f/0x70
irq event stamp: 565512
hardirqs last  enabled at (565511): [<ffffffffb379b138>] __call_rcu_common+0x218/0x940
hardirqs last disabled at (565512): [<ffffffffb5804262>] rcu_torture_init+0x20b2/0x2370
softirqs last  enabled at (399112): [<ffffffffb36b2586>] __local_bh_enable_ip+0x126/0x170
softirqs last disabled at (399106): [<ffffffffb43fef59>] inet_register_protosw+0x9/0x1d0
Preemption disabled at:
[<ffffffffb58040c3>] rcu_torture_init+0x1f13/0x2370
CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W          6.5.0-rc4-rt2-yocto-preempt-rt+ #15
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x68/0xb0
 dump_stack+0x14/0x20
 __might_resched+0x1aa/0x280
 ? __pfx_rcu_torture_err_cb+0x10/0x10
 rt_spin_lock+0x53/0x130
 ? find_vmap_area+0x1f/0x70
 find_vmap_area+0x1f/0x70
 vmalloc_dump_obj+0x20/0x60
 mem_dump_obj+0x22/0x90
 __call_rcu_common+0x5bf/0x940
 ? debug_smp_processor_id+0x1b/0x30
 call_rcu_hurry+0x14/0x20
 rcu_torture_init+0x1f82/0x2370
 ? __pfx_rcu_torture_leak_cb+0x10/0x10
 ? __pfx_rcu_torture_leak_cb+0x10/0x10
 ? __pfx_rcu_torture_init+0x10/0x10
 do_one_initcall+0x6c/0x300
 ? debug_smp_processor_id+0x1b/0x30
 kernel_init_freeable+0x2b9/0x540
 ? __pfx_kernel_init+0x10/0x10
 kernel_init+0x1f/0x150
 ret_from_fork+0x40/0x50
 ? __pfx_kernel_init+0x10/0x10
 ret_from_fork_asm+0x1b/0x30
 </TASK>

The previous patch fixes this by using the deadlock-safe best-effort
version of find_vm_area.  However, in case of failure print the fact that
the pointer was a vmalloc pointer so that we print at least something.

Link: https://lkml.kernel.org/r/20230904180806.1002832-2-joel@joelfernandes.org
Fixes: 98f180837a89 ("mm: Make mem_dump_obj() handle vmalloc() memory")
Signed-off-by: Zqiang <qiang.zhang1211@gmail.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reported-by: Zhen Lei <thunder.leizhen@huaweicloud.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>