| Message ID | alpine.DEB.2.00.1108101516430.20403@router.home (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, 10 Aug 2011 15:21:47 -0500 (CDT) Christoph Lameter <cl@linux.com> wrote: > Some kernel components pin user space memory (infiniband and perf) > (by increasing the page count) and account that memory as "mlocked". > > The difference between mlocking and pinning is: > > A. mlocked pages are marked with PG_mlocked and are exempt from > swapping. Page migration may move them around though. > They are kept on a special LRU list. > > B. Pinned pages cannot be moved because something needs to > directly access physical memory. They may not be on any > LRU list. > > I recently saw an mlockalled process where mm->locked_vm became > bigger than the virtual size of the process (!) because some > memory was accounted for twice: > > Once when the page was mlocked and once when the Infiniband > layer increased the refcount because it needt to pin the RDMA > memory. > > This patch introduces a separate counter for pinned pages and > accounts them seperately. > Sounds reasonable. But how do we prevent future confusion? We should carefully define these terms in an obvious place, please. > --- linux-2.6.orig/include/linux/mm_types.h 2011-08-10 14:08:42.000000000 -0500 > +++ linux-2.6/include/linux/mm_types.h 2011-08-10 14:09:02.000000000 -0500 > @@ -281,7 +281,7 @@ struct mm_struct { > unsigned long hiwater_rss; /* High-watermark of RSS usage */ > unsigned long hiwater_vm; /* High-water virtual memory usage */ > > - unsigned long total_vm, locked_vm, shared_vm, exec_vm; > + unsigned long total_vm, locked_vm, pinned_vm, shared_vm, exec_vm; > unsigned long stack_vm, reserved_vm, def_flags, nr_ptes; > unsigned long start_code, end_code, start_data, end_data; > unsigned long start_brk, brk, start_stack; This is an obvious place. Could I ask that you split all these up into one-definition-per-line and we can start in on properly documenting each field? -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, 17 Aug 2011, Andrew Morton wrote: > Sounds reasonable. But how do we prevent future confusion? We should > carefully define these terms in an obvious place, please. Ok. > > --- linux-2.6.orig/include/linux/mm_types.h 2011-08-10 14:08:42.000000000 -0500 > > +++ linux-2.6/include/linux/mm_types.h 2011-08-10 14:09:02.000000000 -0500 > > @@ -281,7 +281,7 @@ struct mm_struct { > > unsigned long hiwater_rss; /* High-watermark of RSS usage */ > > unsigned long hiwater_vm; /* High-water virtual memory usage */ > > > > - unsigned long total_vm, locked_vm, shared_vm, exec_vm; > > + unsigned long total_vm, locked_vm, pinned_vm, shared_vm, exec_vm; > > unsigned long stack_vm, reserved_vm, def_flags, nr_ptes; > > unsigned long start_code, end_code, start_data, end_data; > > unsigned long start_brk, brk, start_stack; > > This is an obvious place. Could I ask that you split all these up into > one-definition-per-line and we can start in on properly documenting > each field? Will do that after the linuxcon. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Index: linux-2.6/fs/proc/task_mmu.c =================================================================== --- linux-2.6.orig/fs/proc/task_mmu.c 2011-08-10 14:08:42.000000000 -0500 +++ linux-2.6/fs/proc/task_mmu.c 2011-08-10 15:01:37.000000000 -0500 @@ -44,6 +44,7 @@ void task_mem(struct seq_file *m, struct "VmPeak:\t%8lu kB\n" "VmSize:\t%8lu kB\n" "VmLck:\t%8lu kB\n" + "VmPin:\t%8lu kB\n" "VmHWM:\t%8lu kB\n" "VmRSS:\t%8lu kB\n" "VmData:\t%8lu kB\n" @@ -55,6 +56,7 @@ void task_mem(struct seq_file *m, struct hiwater_vm << (PAGE_SHIFT-10), (total_vm - mm->reserved_vm) << (PAGE_SHIFT-10), mm->locked_vm << (PAGE_SHIFT-10), + mm->pinned_vm << (PAGE_SHIFT-10), hiwater_rss << (PAGE_SHIFT-10), total_rss << (PAGE_SHIFT-10), data << (PAGE_SHIFT-10), Index: linux-2.6/include/linux/mm_types.h =================================================================== --- linux-2.6.orig/include/linux/mm_types.h 2011-08-10 14:08:42.000000000 -0500 +++ linux-2.6/include/linux/mm_types.h 2011-08-10 14:09:02.000000000 -0500 @@ -281,7 +281,7 @@ struct mm_struct { unsigned long hiwater_rss; /* High-watermark of RSS usage */ unsigned long hiwater_vm; /* High-water virtual memory usage */ - unsigned long total_vm, locked_vm, shared_vm, exec_vm; + unsigned long total_vm, locked_vm, pinned_vm, shared_vm, exec_vm; unsigned long stack_vm, reserved_vm, def_flags, nr_ptes; unsigned long start_code, end_code, start_data, end_data; unsigned long start_brk, brk, start_stack; Index: linux-2.6/drivers/infiniband/core/umem.c =================================================================== --- linux-2.6.orig/drivers/infiniband/core/umem.c 2011-08-10 14:08:57.000000000 -0500 +++ linux-2.6/drivers/infiniband/core/umem.c 2011-08-10 14:09:06.000000000 -0500 @@ -136,7 +136,7 @@ struct ib_umem *ib_umem_get(struct ib_uc down_write(¤t->mm->mmap_sem); - locked = npages + current->mm->locked_vm; + locked = npages + current->mm->pinned_vm; lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) { @@ -206,7 +206,7 @@ out: __ib_umem_release(context->device, umem, 0); kfree(umem); } else - current->mm->locked_vm = locked; + current->mm->pinned_vm = locked; up_write(¤t->mm->mmap_sem); if (vma_list) @@ -222,7 +222,7 @@ static void ib_umem_account(struct work_ struct ib_umem *umem = container_of(work, struct ib_umem, work); down_write(&umem->mm->mmap_sem); - umem->mm->locked_vm -= umem->diff; + umem->mm->pinned_vm -= umem->diff; up_write(&umem->mm->mmap_sem); mmput(umem->mm); kfree(umem); Index: linux-2.6/drivers/infiniband/hw/ipath/ipath_user_pages.c =================================================================== --- linux-2.6.orig/drivers/infiniband/hw/ipath/ipath_user_pages.c 2011-08-10 14:08:57.000000000 -0500 +++ linux-2.6/drivers/infiniband/hw/ipath/ipath_user_pages.c 2011-08-10 14:09:06.000000000 -0500 @@ -79,7 +79,7 @@ static int __ipath_get_user_pages(unsign goto bail_release; } - current->mm->locked_vm += num_pages; + current->mm->pinned_vm += num_pages; ret = 0; goto bail; @@ -178,7 +178,7 @@ void ipath_release_user_pages(struct pag __ipath_release_user_pages(p, num_pages, 1); - current->mm->locked_vm -= num_pages; + current->mm->pinned_vm -= num_pages; up_write(¤t->mm->mmap_sem); } @@ -195,7 +195,7 @@ static void user_pages_account(struct wo container_of(_work, struct ipath_user_pages_work, work); down_write(&work->mm->mmap_sem); - work->mm->locked_vm -= work->num_pages; + work->mm->pinned_vm -= work->num_pages; up_write(&work->mm->mmap_sem); mmput(work->mm); kfree(work); Index: linux-2.6/drivers/infiniband/hw/qib/qib_user_pages.c =================================================================== --- linux-2.6.orig/drivers/infiniband/hw/qib/qib_user_pages.c 2011-08-10 14:08:57.000000000 -0500 +++ linux-2.6/drivers/infiniband/hw/qib/qib_user_pages.c 2011-08-10 14:09:06.000000000 -0500 @@ -74,7 +74,7 @@ static int __qib_get_user_pages(unsigned goto bail_release; } - current->mm->locked_vm += num_pages; + current->mm->pinned_vm += num_pages; ret = 0; goto bail; @@ -151,7 +151,7 @@ void qib_release_user_pages(struct page __qib_release_user_pages(p, num_pages, 1); if (current->mm) { - current->mm->locked_vm -= num_pages; + current->mm->pinned_vm -= num_pages; up_write(¤t->mm->mmap_sem); } } Index: linux-2.6/kernel/events/core.c =================================================================== --- linux-2.6.orig/kernel/events/core.c 2011-08-10 14:08:57.000000000 -0500 +++ linux-2.6/kernel/events/core.c 2011-08-10 15:04:16.000000000 -0500 @@ -3500,7 +3500,7 @@ static void perf_mmap_close(struct vm_ar struct ring_buffer *rb = event->rb; atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm); - vma->vm_mm->locked_vm -= event->mmap_locked; + vma->vm_mm->pinned_vm -= event->mmap_locked; rcu_assign_pointer(event->rb, NULL); mutex_unlock(&event->mmap_mutex); @@ -3581,7 +3581,7 @@ static int perf_mmap(struct file *file, lock_limit = rlimit(RLIMIT_MEMLOCK); lock_limit >>= PAGE_SHIFT; - locked = vma->vm_mm->locked_vm + extra; + locked = vma->vm_mm->pinned_vm + extra; if ((locked > lock_limit) && perf_paranoid_tracepoint_raw() && !capable(CAP_IPC_LOCK)) { @@ -3607,7 +3607,7 @@ static int perf_mmap(struct file *file, atomic_long_add(user_extra, &user->locked_vm); event->mmap_locked = extra; event->mmap_user = get_current_user(); - vma->vm_mm->locked_vm += event->mmap_locked; + vma->vm_mm->pinned_vm += event->mmap_locked; unlock: if (!ret)
Some kernel components pin user space memory (infiniband and perf) (by increasing the page count) and account that memory as "mlocked". The difference between mlocking and pinning is: A. mlocked pages are marked with PG_mlocked and are exempt from swapping. Page migration may move them around though. They are kept on a special LRU list. B. Pinned pages cannot be moved because something needs to directly access physical memory. They may not be on any LRU list. I recently saw an mlockalled process where mm->locked_vm became bigger than the virtual size of the process (!) because some memory was accounted for twice: Once when the page was mlocked and once when the Infiniband layer increased the refcount because it needt to pin the RDMA memory. This patch introduces a separate counter for pinned pages and accounts them seperately. Signed-off-by: Christoph Lameter <cl@linux.com> --- drivers/infiniband/core/umem.c | 6 +++--- drivers/infiniband/hw/ipath/ipath_user_pages.c | 6 +++--- drivers/infiniband/hw/qib/qib_user_pages.c | 4 ++-- fs/proc/task_mmu.c | 2 ++ include/linux/mm_types.h | 2 +- kernel/events/core.c | 6 +++--- 6 files changed, 14 insertions(+), 12 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html