* Re: + uprobe-use-original-page-when-all-uprobes-are-removed.patch added to -mm tree [not found] <20190726230333.drvM6x-wz%akpm@linux-foundation.org> @ 2019-07-29 15:05 ` Oleg Nesterov 2019-07-29 17:04 ` Song Liu 0 siblings, 1 reply; 4+ messages in thread From: Oleg Nesterov @ 2019-07-29 15:05 UTC (permalink / raw) To: akpm Cc: kirill.shutemov, matthew.wilcox, peterz, rostedt, songliubraving, srikar, william.kucharski, linux-kernel I didn't see this version, so let me reply here. On 07/26, Andrew Morton wrote: > > + /* try orig_page only for unregister and anonymous old_page */ > + if (!is_register && PageAnon(old_page)) { Well, this is confusing... nothing really wrong, but we certainly do not want to install the new anonymous page if !is_register && !PageAnon(old). And in this case we do not even want to call __replace page(). OK, I won't insist, this should almost never happen, but again, please see https://lore.kernel.org/lkml/20190726084423.GA16112@redhat.com/ > + struct page *orig_page; > + pgoff_t index; > + > + index = vaddr_to_offset(vma, vaddr & PAGE_MASK) >> PAGE_SHIFT; > + orig_page = find_get_page(vma->vm_file->f_inode->i_mapping, > + index); > + > + if (orig_page) { > + if (PageUptodate(orig_page) && > + pages_identical(new_page, orig_page)) { > + /* let go new_page */ > + put_page(new_page); > + new_page = NULL; > + > + /* dec_mm_counter for old_page */ > + dec_mm_counter(mm, MM_ANONPAGES); this assumes that __replace_page() can't fail, but it can. I think you should move this into into __replace_page(). Oleg. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: + uprobe-use-original-page-when-all-uprobes-are-removed.patch added to -mm tree 2019-07-29 15:05 ` + uprobe-use-original-page-when-all-uprobes-are-removed.patch added to -mm tree Oleg Nesterov @ 2019-07-29 17:04 ` Song Liu 2019-07-30 19:17 ` Andrew Morton 0 siblings, 1 reply; 4+ messages in thread From: Song Liu @ 2019-07-29 17:04 UTC (permalink / raw) To: Oleg Nesterov Cc: Andrew Morton, Kirill A. Shutemov, Matthew Wilcox, Peter Zijlstra, Steven Rostedt, Srikar Dronamraju, William Kucharski, linux-kernel > On Jul 29, 2019, at 8:05 AM, Oleg Nesterov <oleg@redhat.com> wrote: > > I didn't see this version, so let me reply here. > > On 07/26, Andrew Morton wrote: >> >> + /* try orig_page only for unregister and anonymous old_page */ >> + if (!is_register && PageAnon(old_page)) { > > Well, this is confusing... nothing really wrong, but we certainly do not > want to install the new anonymous page if !is_register && !PageAnon(old). > And in this case we do not even want to call __replace page(). > > OK, I won't insist, this should almost never happen, but again, please > see https://lore.kernel.org/lkml/20190726084423.GA16112@redhat.com/ I see. Do you want me fold this patch with 2/4? > >> + struct page *orig_page; >> + pgoff_t index; >> + >> + index = vaddr_to_offset(vma, vaddr & PAGE_MASK) >> PAGE_SHIFT; >> + orig_page = find_get_page(vma->vm_file->f_inode->i_mapping, >> + index); >> + >> + if (orig_page) { >> + if (PageUptodate(orig_page) && >> + pages_identical(new_page, orig_page)) { >> + /* let go new_page */ >> + put_page(new_page); >> + new_page = NULL; >> + >> + /* dec_mm_counter for old_page */ >> + dec_mm_counter(mm, MM_ANONPAGES); > > this assumes that __replace_page() can't fail, but it can. I think you > should move this into into __replace_page(). Good catch! Let me fix it. Hi Andrew, Do you prefer a whole v10 (1/4 to 4/4) or just newer version of this one (2/4)? Thanks, Song ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: + uprobe-use-original-page-when-all-uprobes-are-removed.patch added to -mm tree 2019-07-29 17:04 ` Song Liu @ 2019-07-30 19:17 ` Andrew Morton 2019-07-30 19:28 ` Song Liu 0 siblings, 1 reply; 4+ messages in thread From: Andrew Morton @ 2019-07-30 19:17 UTC (permalink / raw) To: Song Liu Cc: Oleg Nesterov, Kirill A. Shutemov, Matthew Wilcox, Peter Zijlstra, Steven Rostedt, Srikar Dronamraju, William Kucharski, linux-kernel On Mon, 29 Jul 2019 17:04:05 +0000 Song Liu <songliubraving@fb.com> wrote: > > this assumes that __replace_page() can't fail, but it can. I think you > > should move this into into __replace_page(). > > Good catch! Let me fix it. > > Hi Andrew, > > Do you prefer a whole v10 (1/4 to 4/4) or just newer version of this > one (2/4)? Either is OK. I guess just a new 2/4 is sufficient, if the difference is minor. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: + uprobe-use-original-page-when-all-uprobes-are-removed.patch added to -mm tree 2019-07-30 19:17 ` Andrew Morton @ 2019-07-30 19:28 ` Song Liu 0 siblings, 0 replies; 4+ messages in thread From: Song Liu @ 2019-07-30 19:28 UTC (permalink / raw) To: Andrew Morton Cc: Oleg Nesterov, Kirill A. Shutemov, Matthew Wilcox, Peter Zijlstra, Steven Rostedt, Srikar Dronamraju, William Kucharski, linux-kernel > On Jul 30, 2019, at 12:17 PM, Andrew Morton <akpm@linux-foundation.org> wrote: > > On Mon, 29 Jul 2019 17:04:05 +0000 Song Liu <songliubraving@fb.com> wrote: > >>> this assumes that __replace_page() can't fail, but it can. I think you >>> should move this into into __replace_page(). >> >> Good catch! Let me fix it. >> >> Hi Andrew, >> >> Do you prefer a whole v10 (1/4 to 4/4) or just newer version of this >> one (2/4)? > > Either is OK. I guess just a new 2/4 is sufficient, if the difference > is minor. I sent v10 last night. Then Oleg found some issue with 3/4 (thanks!) Let me resend 2/4 (with change in commit log) and 3/4 (with code change). Thanks, Song ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-07-30 19:29 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <20190726230333.drvM6x-wz%akpm@linux-foundation.org> 2019-07-29 15:05 ` + uprobe-use-original-page-when-all-uprobes-are-removed.patch added to -mm tree Oleg Nesterov 2019-07-29 17:04 ` Song Liu 2019-07-30 19:17 ` Andrew Morton 2019-07-30 19:28 ` Song Liu
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